Patent Application
20110251403
The present invention relates to a method for manufacturing a hydroxyl group substitution product, which is important as intermediates for pharmaceutical and agricultural chemicals.
Hydroxyl group substitution products are important as intermediates for pharmaceutical and agricultural chemicals. There have been disclosed, as conventional manufacturing techniques relevant to the present invention, a Mitsunobu reaction process that uses diethyl azodicarboxylate (DEAD) and triphenyl phosphine (Patent Document 1) and a process that forms a mesyloxy group as a leaving group and then reacts the mesyloxy group with a nucleophile (Non-Patent Document 1).
The present applicant has disclosed a process for dehydroxyfluorination of an alcohol by the combined use of an organic base and sulfuryl fluoride (SO2F2) (Patent Document 2).
It is an object of the present invention to provide an industrial manufacturing method of a hydroxyl group substitution product. In order to achieve the object of the present invention, it is necessary to solve the following problems in the prior art techniques.
The process of Patent Document 1 needs to use diethyl azodicarboxylate and triphenyl phosphine, which are relatively expensive for large-scale applications. Further, the process of Patent Document 1 stoichiometrically generates a by-product difficult to separate from the target compound and thus requires complicated purification operation such as column chromatography.
The process of Non-Patent Document 1 proceeds in two process steps by way of a reactive intermediate and presents problems such as process complication and increase in waste associated with such process complication.
The process of Patent Document 2 generates a fluorosulfuric acid ester and a fluorine anion (F−) in the reaction system. As the fluorosulfuric acid ester undergoes substitution reaction with the fluorine anion very rapidly, it has been totally unknown whether the target hydroxyl group substitution product of the present invention can be obtained selectively in preference to the fluorination product even when the reaction process is conducted in the presence of any nucleophile (X−) other than the fluorine anion as in the present invention (see Scheme 1).
As mentioned above, there has been a strong demand for an industrial manufacturing method that uses a relatively cheap reagent suitable for large-scale applications and can be accomplished in a simple process with easy purification operation and less waste generation.
The present inventors have made extensive researches in view of the above problems and, as a result, have found that it is possible to manufacture a hydroxyl group substitution product by reaction of an alcohol with sulfuryl fluoride in the presence of a specific nucleophile and an organic base. As the raw substrate, preferred are optically active alcohols, more preferably an optically active α-hydroxyester and an optically active 4-hydroxyproline, as the resulting optically active hydroxyl group substitution products (notably, optically active α-hydroxyl group substitution ester and optically active 4-hydroxyl group substitution proline) are very important as intermediates for pharmaceutical and agricultural chemicals.
The manufacturing conditions of the present invention are similar to the dehydroxyfluorination reaction conditions of Patent Document 2. The present inventors have however found that, when the reaction is conducted in the presence of the specific nucleophile other than fluorine anion, it is possible that the hydroxyl group substitution product derived from the nucleophile can be obtained selectively in preference to fluorinated compounds. In the present invention, the nucleophile is a monovalent anion represented by X−. As a species X that constitutes the nucleophile X−, there can be used a halogen atom such as chlorine, bromine or iodine, an azide group, a nitrooxy group, a cyano group, a thiocyanate group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group and a substituted arylcarbonyloxy group. Among others, a halogen atom such as chlorine, bromine or iodine, an azide group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group and a substituted arylcarbonyloxy group are preferred. Particularly preferred are a halogen atom such as chlorine, bromine or iodine and an azide group. The desired reaction proceeds very favorably though the use of such a nucleophile.
In this way, the present inventors have found the very useful techniques for manufacturing of the hydroxyl group substitution product. The present invention is based on these findings.
Namely, the present invention provides an industrial method for manufacturing a hydroxyl group substitution product as set forth below in Inventive Aspects 1 to 4.
[Inventive Aspect 1]
A method for manufacturing a hydroxyl group substitution product of the general formula [2], comprising: reacting an alcohol of the general formula [1] with sulfuryl fluoride (SO2F2) in the presence of an organic base and a nucleophile (X−),
where R1, R2 and R3 each independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aromatic ring group, a substituted aromatic ring group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group or a cyano group; when two of R1, R2 and R3 are any substituent groups other than hydrogen atom, formyl group, aminocarbonyl group and cyano group, these two substituent groups may form a ring structure by a covalent bond between carbon atoms thereof through or without a heteroatom; and X represents a halogen atom selected from the group consisting of chlorine, bromine and iodine, an azide group, a nitrooxy group, a cyano group, a thiocyanate group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group or a substituted arylcarbonyloxy group.
[Inventive Aspect 2]
A method for manufacturing an optically active hydroxyl group substitution product of the general formula [4], comprising: reacting an optically active alcohol of the general formula [3] with sulfuryl fluoride (SO2F2) in the presence of an organic base and a nucleophile (Y−),
where R4 and R5 each independently represent an alkyl group, a substituted alkyl group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group or a cyano group; R4 and R5 are in kind different from each other; when R4 and R5 represent any two substituent groups other than formyl group, aminocarbonyl group and cyano group, these two substituent groups may form a ring structure by a covalent bond between carbon atoms thereof through or without a heteroatom; Y represents a halogen atom selected from the group consisting of chlorine, bromine and iodine, an azide group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group or a substituted arylcarbonyloxy group; * represents an asymmetric carbon atom; and the configuration of the asymmetric carbon atom is inverted in the reaction.
[Inventive Aspect 3]
A method for manufacturing an optically active α-hydroxyl group substitution ester of the general formula [6], comprising: reacting an optically active α-hydroxyester of the general formula [5] with sulfuryl fluoride (SO2F2) in the presence of an organic base and a nucleophile (Z−),
where R6 and R7 each independently represent an alkyl group or a substituted alkyl group and may form a ring structure by a covalent bond between carbon atoms thereof through or without a heteroatom; Z represents a halogen atom selected from the group consisting of chlorine, bromine and iodine or an azide group; * represents an asymmetric carbon atom; and the configuration of the asymmetric carbon atom is inverted in the reaction.
[Inventive Aspect 4]
A method for manufacturing an optically active 4-hydroxyl group substitution proline of the general formula [8], comprising: reacting an optically active 4-hydroxyproline of the general formula [7] with sulfuryl fluoride (SO2F2) in the presence of an organic base and a nucleophile (Z−),
where R8 represents a secondary amino protecting group; R9 represents a carboxyl protecting group; Z represents a halogen atom selected from the group consisting of chlorine, bromine and iodine or an azide group; and * each represent an asymmetric carbon atom; the configuration of the asymmetric carbon atom at 2-position is maintained throughout the reaction; and the configuration of the asymmetric carbon atom at 4-position is inverted in the reaction.
The advantages of the present invention over the prior art techniques will be explained below.
In the present invention, sulfuryl fluoride is used as a reagent. This reagent is widely adapted as a fumigant and is available at low cost for large-scale applications. Further, it is possible in the present invention to achieve a simple reaction process with easy purification operation and less waste generation as the reaction proceeds in a single process step and generates no by-product difficult to separate from the target compound. It is also possible that, by the use of the alcohol substrate of high optical purity, the hydroxyl group substitution product of high optical purity can be obtained upon inversion of the configuration of the asymmetric carbon atom as the configuration of the asymmetric carbon atom is highly inverted in the reaction.
As mentioned above, the manufacturing method of the present invention solves all of the prior art problems and can be applied for industrial uses.
The manufacturing method of the hydroxyl group substitution product according to the present invention will be described in detail below.
In the present invention, a hydroxyl group substitution product of the general formula [2] is manufactured by reaction of an alcohol of the general formula [1] with sulfuryl fluoride in the presence of an organic base and a nucleophile.
In the alcohol of the general formula [1], R1, R2 and R3 each independently represents a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aromatic ring group, a substituted aromatic ring group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group or a cyano group. The alcohol is preferably an optically active alcohol in which one of the three substituent groups is an hydrogen atom and two of the three substituent groups are different in kind from each other and are each independently an alkyl group, a substituted alkyl group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group or a cyano group. Particularly preferred are: an optically active α-hydroxyester in which one of the three substituent groups is a hydrogen atom, another one of the three substituent groups is an alkoxycarbonyl group or a substituted alkoxycarbonyl group and the other one of the three substituent group is an alkyl group or a substituted alkyl group; and an optically active 4-hydroxyproline in which a secondary amino group and an carboxyl group are protected by protecting groups, respectively.
The alkyl group can have 1 to 18 carbon atoms and can be in the form of a linear or branched structure, or a cyclic structure (in the case of 3 or more carbon atoms). The alkenyl group refers to a group in which any number of single bonds between any two adjacent carbon atoms of the above alkyl group has been replaced with a double bond. In the alkenyl group, the double bond can be in an E-configuration, a Z-configuration or a mixture thereof (the alkenyl carbon (SP2 carbon) may not be linked directly to the carbon to which the hydroxyl group is bonded). The alkynyl group refers to a group in which any number of single bonds between any two adjacent carbon atoms of the above alkyl group has been replaced with a triple bond (the alkynyl carbon (SP carbon) may not be linked directly to the carbon to which the hydroxyl group is bonded). The aromatic ring group can have 1 to 18 carbon atoms and can be in the form of an aromatic hydrocarbon group, such as phenyl, naphthyl or anthryl, or an aromatic heterocyclic group containing a heteroatom e.g. nitrogen, oxygen or sulfur, such as pyrrolyl, furyl, thienyl, indolyl, benzofuryl or benzothienyl. The formyl group refers to a group represented by —COH. The alkyl moiety (R) of the alkylcarbonyl group (—COR) has the same definition as that of the above alkyl group. The aryl moiety (Ar) of the arylcarbonyl group (—COAr) has the same definition as that of the above aromatic ring group. The alkyl moiety (R) of the alkoxycarbonyl group (—CO2R) has the same definition as that the above alkyl group. The aminocarbonyl group refers to a group represented by —CONH2. The alkyl moiety (R) of the alkylaminocarbonyl group (—CONHR or —CONR2) has the same definition as that of the above alkyl group. The aryl moiety (Ar) of the arylaminocarbonyl group (—CONHAr or —CONAr2) has the same definition as that of the above aromatic ring group.
Any of the carbon atoms of the alkyl group, the alkenyl group, the alkynyl group, the aromatic ring group, the alkylcarbonyl group, the arylcarbonyl group, the alkoxycarbonyl group, the alkylaminocarbonyl group and the arylaminocarbonyl group may be replaced with any number of and any combination of substituents (which correspond to the substituted alkyl group, the substituted alkenyl group, the substituted alkynyl group, the substituted aromatic ring group, the substituted alkylcarbonyl group, the substituted arylcarbonyl group, the substituted alkoxycarbonyl group, the substituted alkylaminocarbonyl group and the substituted arylaminocarbonyl group, respectively). Examples of such substituents are: halogen atoms such as fluorine, chlorine, bromine and iodine; azide group; nitro group; lower alkyl groups such as methyl, ethyl and propyl; lower haloalkyl groups such as fluoromethyl, chloromethyl and bromomethyl; lower alkoxy groups such as methoxy, ethoxy and propoxy; lower haloalkoxy groups such as fluoromethoxy, chloromethoxy and bromomethoxy; lower alkylamino groups such as dimethylamino, diethylamino and dipropylamino; lower alkylthio groups such as methylthio, ethylthio and propylthio; cyano group; lower alkoxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl and propoxycarbonyl; aminocarbonyl group; lower alkylaminocarbonyl groups such as dimethylaminocarbonyl, diethylaminocarbonyl and dipropylaminocarbonyl; unsaturated groups such as lower alkenyl groups and lower alkynyl groups; aromatic ring groups such as phenyl, naphthyl, pyrrolyl, furyl and thienyl; aromatic ring oxy groups such as phenoxy, naphthoxy, pyrrolyloxy, furyloxy and thienyloxy; aliphatic heterocyclic groups such as piperidyl, piperidino and morpholinyl; hydroxyl group; protected hydroxyl groups; amino group; protected amino groups (including amino acids and peptide residues); thiol group; protected thiol groups; aldehyde group; protected aldehyde groups; carboxyl group; and protected carboxyl groups.
The following terms are herein defined by the following meanings in the present specification. The term “lower” means that the group to which the term is attached has 1 to 6 carbon atoms in the form of a linear structure, a branched structure or a cyclic structure (in the case of 3 or more carbon atoms). It means that, when the “unsaturated group” is a double bond (alkenyl group), the double bond can be in an E-configuration, a Z-configuration or a mixture thereof. The “protected hydroxyl, amino, thiol, aldehyde and carboxyl groups” may refer to those having protecting groups as described in “Protective Groups in Organic Synthesis”, Third Edition, 1999, John Wiley & Sons, Inc. (In this case, two or more functional groups may be protected with one protecting group.) Further, the “unsaturated group”, “aromatic ring group”, “aromatic ring oxy group” and “aliphatic heterocyclic group” may be substituted with halogen atoms, azide group, nitro group, lower alkyl groups, lower haloalkyl groups, lower alkoxy groups, lower haloalkoxy groups, lower alkylamino groups, lower alkylthio groups, cyano group, lower alkoxycarbonyl groups, aminocarbonyl group, lower alkylaminocarbonyl groups, hydroxyl group, protected hydroxyl groups, amino group, protected amino groups, thiol group, protected thiol groups, aldehyde group, protected aldehyde groups, carboxyl group or protected carboxyl groups. Although some of these substituent groups may react with sulfuryl fluoride in the presence of the organic base and the nucleophile, the desired reaction can be promoted favorably by adoption of the suitable reaction conditions.
When two of the substituent groups R1, R2 and R3 are any other than hydrogen atom, formyl group, aminocarbonyl group and cyano group in the alcohol of the general formula [1], these two substituent groups may form a ring structure by a covalent bond between two carbon atoms thereof through or without a heteroatom (e.g. nitrogen, oxygen, sulfur etc.).
The carbon atom to which the hydroxyl group is bonded is an asymmetric carbon atom when the substituent groups R1, R2 and R3 are different in kind from one another in the alcohol of the general formula [1]. The configuration of this asymmetric carbon atom is inverted in the reaction. In the case where the target compound is in the form of an optically active substance, an optically active alcohol is used as the raw substrate. (It is needless to say that the raw substrate can be a racemic mixture of the alcohol depending on the target compound.)
In the optically active alcohol of the general formula [3], R4 and R5 each independently represent an alkyl group, a substituted alkyl group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group, or a cyano group. These substituent groups are R4 and R5 different in kind from each other. Specific examples of the substituent groups R4 and R5 are the same as those of R1, R2, R3 in the alcohol of the general formula [1].
When the substituent groups R4 and R5 are any other than formyl group, aminocarbonyl group and cyano group in the optically active alcohol of the general formula [3], these substituent groups may form a ring structure by a covalent bond between two carbon atoms thereof through or without a heteroatom (e.g. nitrogen, oxygen, sulfur etc.) (whereby the optically active alcohol can be, for example, an optically active hydroxycycloalkane).
In the optically active alcohol of the general formula [3], * represents an asymmetric carbon atom. The configuration of this asymmetric carbon atom is inverted in the reaction.
The asymmetric carbon atom of the optically active alcohol of the general formula [3] can be in a R-configuration and/or S-configuration. The configuration of the asymmetric carbon atom of the optically active alcohol of the general formula [3] can be selected as appropriate depending on the absolute configuration of the target compound. It suffices that the optical purity of the optically active alcohol of the general formula [3] is 70% ee or higher (enantiomer excess). The optical purity of the optically active alcohol of the general formula [3] is generally preferably 80% ee or higher, more preferably 90% ee or higher.
In the optically active α-hydroxyester of the general formula [5], R6 and R7 each independently represent an alkyl group or a substituted alkyl group. Specific examples of the substituent groups R6 and R7 are the same as those of R1, R2, R3 in the alcohol of the general formula [1].
The substituent groups R6 and R7 may form a ring structure by a covalent bond between two carbon atoms thereof through or without a heteroatom (e.g. nitrogen, oxygen, sulfur etc.) in the optically active α-hydroxyester of the general formula [5] (whereby the optically active α-hydroxyester can be, for example, an optically active α-hydroxylactone).
In the optically active α-hydroxyester of the general formula [5], * represents an asymmetric carbon atom. The configuration of this asymmetric carbon atom is inverted in the reaction.
The asymmetric carbon atom of the optically active α-hydroxyester of the general formula [5] can be in a R-configuration and/or S-configuration. The configuration of the asymmetric carbon atom of the optically active α-hydroxyester of the general formula [5] can be selected as appropriate depending on the absolute configuration of the target compound. It suffices that the optical purity of the optically active α-hydroxyester of the general formula [5] is 80% ee or higher. The optical purity of the optically active α-hydroxyester of the general formula [5] is generally preferably 90% ee or higher, more preferably 95% ee or higher.
As a suitable raw substrate of the present invention, the optically active α-hydroxyester of the general formula [5] can be prepared from various commercially available optically active α-amino acids in the same manner as disclosed in Synthetic Communications (U.S.), 1991, Vol. 21, P. 2165-2170 etc. Some forms of the optically active α-hydroxyester are commercially available and usable as the raw substrate. For example, there was used commercially available ethyl ester of (S)-lactic acid in the after-mentioned examples. Further, the alcohol of the general formula [1] and the optically active alcohol of the general formula [3] are commercially available in various forms.
In the optically active 4-hydroxyproline of the general formula [7], R8 represents a secondary amino protecting group. Examples of the secondary amino protecting group are benzyloxycarbonyl, tert-butoxycarbonyl, 9-fluorenylmethoxycarbonyl, 3-nitro-2-pyridinesulfenyl and p-methoxybenzyloxycarbonyl.
Among others, benzyloxycarbonyl and tert-butoxycarbonyl are preferred. Particularly preferred is tert-butoxycarbonyl.
In the optically active 4-hydroxyproline of the general formula [7], R9 represents a carboxyl protecting group. Examples of the carboxyl protecting group are methyl, ethyl, tert-butyl, trichloroethyl, phenacyl, benzyl, 4-nitrobenzyl and 4-methoxybenzyl. Among others, methyl, ethyl, tert-butyl and benzyl are preferred. Particularly preferred are methyl and ethyl.
As a suitable raw substrate of the present invention, the optically active 4-hydroxyproline of the general formula [7] can be prepared from commercially available optically active 4-hydroxyproline in the same manner as disclosed in Jikken Kagaku Koza, Fourth Edition, Vol. 22, Organic Synthesis IV, Acids, Amino Acids and Peptides (published by Maruzen Co., Ltd., 1992, P. 193-309) etc. Some forms of the optically active 4-hydroxyproline are commercially available and usable as the raw substrate depending on the combination of the secondary amino protecting group R8 and the carboxyl protecting group R9. Further, the optically active 4-hydroxyproline of the general formula [7] can be readily prepared, in compound form where the secondary amino protecting group R8 is tert-butoxycarbonyl and the carboxyl protecting group R9 is methyl (S-configuration at 2-position, R-configuration at 4-position), from hydrochloride of optically active 4-hydroxyproline methyl ester according to Tetrahedron Letters (UK), 1998, Vol. 39, P. 1169-1172.
In optically active 4-hydroxyproline of the general formula [7], * each represent an asymmetric carbon atom. The configuration of the asymmetric carbon atom at 2-position is maintained throughout the reaction, whereas the configuration of the asymmetric carbon atom at 4-position is inverted in the reaction.
The configurations of the two asymmetric carbon atoms of the optically active 4-hydroxyproline of the general formula [7] can be selected as appropriate depending on the absolute configuration of the target compound. The following combinations of the configurations of the two asymmetric carbon atoms of the optically active 4-hydroxyproline of the general formula [7] are possible: R-configuration at 2-position/R-configuration at 4-position; R-configuration at 2-position/S-configuration at 4-position; S-configuration at 2-position/R-configuration at 4-position; and S-configuration at 2-position/S-configuration at 4-position. It suffices that the enantiomer excess of the optically active 4-hydroxyproline of the general formula [7] is 80% ee or higher. The enantiomer excess of the optically active 4-hydroxyproline of the general formula [7] is generally preferably 90% ee or higher, more preferably 95% ee or higher. Further, it suffices that the diastereoisomer excess of the optically active 4-hydroxyproline of the general formula [7] is 80% de or higher. The diastereoisomer excess of the optically active 4-hydroxyproline of the general formula [7] is generally preferably 90% de or higher, more preferably 95% de or higher.
Examples of the organic base are trimethylamine, triethylamine, diisopropylethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, pyridine, 2,3-lutidine, 2,4-lutidine, 2,5-lutidine, 2,6-lutidine, 3,4-lutidine, 3,5-lutidine, 2,3,4-collidine, 2,4,5-collidine, 2,5,6-collidine, 2,4,6-collidine, 3,4,5-collidine, 3,5,6-collidine, 4-dimethylaminopyridine, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), N,N,N′,N′,N″-pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and phosphazene bases e.g. BEMP and t-Bu-P4. Among others, triethylamine, diisopropylethylamine, tri-n-butylamine, pyridine, 2,6-lutidine, 2,4,6-collidine, 4-dimethylaminopyridine, 1,5-diazabicyclo[4.3.0]non-5-ene and 1,8-diazabicyclo[5.4.0]undec-7-ene are preferred. Particularly preferred are triethylamine, diisopropylethylamine, tri-n-butylamine, pyridine, 2,6-lutidine, 2,4,6-collidine and 1,8-diazabicyclo[5.4.0]undec-7-ene. These organic bases can be used solely or in combination thereof.
It suffices to use the organic base in an amount of 0.6 mol or more per 1 mol of the alcohol of the general formula [1]. The amount of the organic base used is preferably 0.7 to 10 mol, more preferably 0.8 to 5 mol, per 1 mol of the alcohol of the general formula [1].
The nucleophile constituting species X, which constitutes the nucleophile (X−), is a halogen atom such as chlorine, bromine or iodine, an azide group, a nitrooxy group, a cyano group, a thiocyanate group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group or a substituted arylcarbonyloxy group. Among others, a halogen atom such as chlorine, bromine or iodine, an azide group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group and a substituted arylcarbonyloxy group are preferred. Particularly preferred are a halogen atom such as chlorine, bromine or iodine and an azide group. Herein, the nitrooxy group refers to a group represented by ONO2; and the formyloxy group refers to a group represented by OCOH. The alkyl moiety (R) of the alkylcarbonyloxy group (OCOR) and the substituted alkyl moiety (R′) of the substituted alkylcarbonyloxy group (OCOR′) have the same definitions as those of R1, R2, R3 in the alcohol of the general formula [1]. The aryl moiety (Ar) of the arylcarbonyloxy group (OCOAr) and the substituted aryl moiety of the substituted arylcarbonyloxy group (OCOAr′) have the same definitions as those of R1, R2, R3 in the alcohol of the general formula [1].
The nucleophile (X) may be in the form of a salt with a counter cation. Alternatively, the nucleophile (X−) may be in the form of a neutral molecule in which the atom X is involved in a covalent bond so that the anion X− is liberated from the neutral molecule and functions as the nucleophile in the reaction system.
Examples of the counter cation (or the covalent bond group (the counter group of the covalent bond) of the neutral molecule) usable in combination with the nucleophile (X) are: monovalent cations of alkali metals such as lithium, sodium, potassium and cesium; divalent cations of alkaline-earth metals such as magnesium and calcium; monovalent or divalent cations of Group-11 (IB) transition metals such as copper and silver; monovalent cations of quaternary ammoniums such as tetramethylammonium, tetraethylammonium and tetrabutylammonium; monovalent cations of quaternary phosphoniums such as tetramethylphosphonium, tetraethylphosphonium and tetrabutylphosphonium; monovalent covalent bond groups of trialkylsilyls such as trimethylsilyl, triethylsilyl and tert-butyldimethylsilyl; and monovalent covalent bonds of phosphoryls such as diphenylphosphoryl. Among others, monovalent cations of alkali metals, divalent cations of alkaline-earth metals, monovalent cations of quaternary ammoniums and monovalent cations of quaternary phosphoniums are preferred. Particularly preferred are monovalent cations of alkali metals, divalent cations of alkaline-earth metals and monovalent cations of quaternary ammoniums. These counter cations (or neutral molecule's covalent bond groups) can be used solely or in combination thereof. As quaternary ammoniums and quaternary phosphoniums are often used as phase transfer catalysts for organic synthesis, the combined use of “an alkali metal salt or alkaline-earth metal salt” and “a quaternary ammonium salt or quaternary phosphonium salt” provides the same effect as in the case where the reaction with the alkali metal salt or alkaline-earth metal salt is conducted in the presence of the phase transfer catalyst. It is thus one preferred embodiment of the present invention to use “alkali metal salt or alkaline-earth metal salt” in combination with “quaternary ammonium salt or quaternary phosphonium salt”.
Preferred combinations of the counter cation (neutral molecule's covalent bond group) and the species X constituting the nucleophile (X) are: monovalent alkali metal cation/halogen atom; divalent alkaline-earth metal cation/halogen atoms (two atoms); monovalent quaternary ammonium cation/halogen atom; monovalent quaternary phosphonium cation/halogen atom; monovalent alkali metal cation/azide group; divalent alkaline-earth metal cation/azide groups (two groups); monovalent quaternary ammonium cation/azide group; monovalent quaternary phosphonium cation/azide group; monovalent alkali metal cation/formyloxy group; divalent alkaline-earth metal cation/formyloxy groups (two groups); monovalent quaternary ammonium cation/formyloxy group; monovalent quaternary phosphonium cation/formyloxy group; monovalent alkali metal cation/alkylcarbonyloxy group; divalent alkaline-earth metal cation/alkylcarbonyloxy groups (two groups); monovalent quaternary ammonium cation/alkylcarbonyloxy group; monovalent quaternary phosphonium cation/alkylcarbonyloxy group; monovalent alkali metal cation/substituted alkylcarbonyloxy group; divalent alkaline-earth metal cation/substituted alkylcarbonyloxy groups (two groups); monovalent quaternary ammonium cation/substituted alkylcarbonyloxy group; monovalent quaternary phosphonium cation/substituted alkylcarbonyloxy group; monovalent alkali metal cation/arylcarbonyloxy group; divalent alkaline-earth metal cation/arylcarbonyloxy groups (two groups); monovalent quaternary ammonium cation/arylcarbonyloxy group; monovalent quaternary phosphonium cation/arylcarbonyloxy group; monovalent alkali metal cation/substituted arylcarbonyloxy group; divalent alkaline-earth metal cation/substituted arylcarbonyloxy groups (two groups); monovalent quaternary ammonium cation/substituted arylcarbonyloxy group; and monovalent quaternary phosphonium cation/substituted arylcarbonyloxy group. Particularly preferred are: monovalent alkali metal cation/halogen atom; divalent alkaline-earth metal cation/halogen atoms (two atoms); monovalent quaternary ammonium cation/halogen atom; monovalent alkali metal cation/azide group; divalent alkaline-earth metal cation/azide groups (two groups); and monovalent quaternary ammonium cation/azide group.
As the nucleophile (X−), there can also suitably be used a “salt or complex” consisting of “any of hydrogen halides such as hydrogen chloride, hydrogen bromide and hydrogen iodide, hydrogen azide, nitric acid, hydrogen cyanide, thiocyanic acid, formic acid, aliphatic carboxylic acid, substituted aliphatic carboxylic acid, aromatic carboxylic acid and substituted aromatic carboxylic acid (hereinafter referred to as “component A”)” and “any of the above-mentioned organic bases usable in the present invention (hereinafter referred to as “component B”)”. It suffices that the mole ratio of the components A and B of the salt or complex is in the range of 100:1 to 1:100. The mole ratio of the components A and B of the salt or complex is preferably in the range of 50:1 to 1:50, more preferably 25:1 to 1:25. The salt or complex can be readily prepared by mixing the components A and B at a desired ratio with caution given to heat generation. It is particularly convenient to prepare the salt or complex in the after-mentioned reaction solvent and directly use the resulting solution for the reaction. As a matter of course, a commercially available product of this salt or complex is also usable. In view of the fact that, in Scheme 1, sulfonylation favorably proceeds under basic conditions, it is effective to increase the amount of the above-mentioned organic base used and thereby place the reaction system under basic conditions in the case where the mole ratio of the component A is significantly higher than that of the component B.
It suffices to use the nucleophile (X−) in an amount of 0.6 mol or more per 1 mol of the alcohol of the general formula [1]. The amount of the nucleophile (X−) used is preferably 0.7 to 10 mol, more preferably 0.8 to 5 mol, per 1 mol of the alcohol of the general formula [1].
Further, it suffices to use the sulfuryl fluoride in an amount of 0.7 mol or more per 1 mol of the alcohol of the general formula [1]. The amount of the sulfuryl fluoride used is 0.8 to 10 mol, more preferably 0.9 to 5 mol, per 1 mol of the alcohol of the general formula [1].
Examples of the reaction solvent are: aliphatic hydrocarbon solvents such as n-hexane, cyclohexane and n-heptane; aromatic hydrocarbon solvents such as benzene, toluene, ethylbenzene, xylene and mesitylene; halogenated hydrocarbon solvents such as methylene chloride, chloroform and 1,2-dichloroethane; ether solvents such as diethyl ether, tetrahydrofuran, diisopropyl ether and tert-butyl methyl ether, ester solvents such as ethyl acetate and n-butyl acetate; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolizine; nitrile solvents such as acetonitrile and propionitrile; and dimethyl sulfoxide. Among others, n-hexane, n-heptane, toluene, xylene, mesitylene, methylene chloride, tetrahydrofuran, diisopropyl ether, tert-butyl methyl ether, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, propionitrile and dimethyl sulfoxide are preferred. Particularly preferred are toluene, xylene, methylene chloride, tetrahydrofuran, tert-butyl methyl ether, ethyl acetate, N,N-dimethylformamide and acetonitrile. These reaction solvents can be used solely or in combination thereof.
It suffices to use the reaction solvent in an amount of 0.05 L or more per 1 mol of the alcohol of the general formula [1]. The amount of the reaction solvent used is 0.1 to 20 L, more preferably 0.2 to 10 L, per 1 mol of the alcohol of the general formula [1].
It suffices that the reaction temperature is in the range of −60 to +100° C. The reaction temperature is preferably −40 to +80° C., more preferably −20 to +60° C.
Further, it suffices that the reaction time is 48 hours or less. As the reaction time depends on the raw substrate and the reaction conditions, it is preferable to determine the time at which the raw substrate has almost disappeared as the end of the reaction while monitoring the progress of the reaction by any analytical means such as gas chromatography, liquid chromatography or nuclear magnetic resonance.
The hydroxyl group substitution group of the general formula [2] can be obtained as a crude product by post treatment of the reaction terminated liquid. As one example of post treatment operation, it is feasible to concentrate the reaction terminated liquid as appropriate, dilute the concentrated liquid with organic solvent (such as n-hexane, n-heptane, toluene, xylene, methylene chloride, diisopropyl ether, tert-butyl methyl ether, ethyl acetate etc.), wash the diluted liquid with water, aqueous solution of inorganic acid (such as hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid etc.) or aqueous solution of inorganic base (such as sodium hydrogencarbonate, potassium hydrogencarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide etc.), (dry the recovered organic layer with a drying agent such as anhydrous sodium sulfate, anhydrous magnesium sulfate etc. as needed,) and then, concentrate the recovered organic layer. There may be some quaternary ammonium salt or quaternary phosphonium salt remaining in the crude product. In this case, it is feasible to extract the salt and the target compound with an organic solvent against which the salt and the target compound show a difference in solubility (such as n-hexane, n-heptane, toluene, xylene etc.) so that the target compound and the salt can be readily separated by simple operation such as filtration. It is also effective to use a short column of silica or alumina for removal of the salt. Further, the crude product can be purified to a high chemical purity, as required, by purification operation such as activated carbon treatment, distillation, recrystallization or column chromatography. When the target hydroxyl group substitution product is unstable, it is feasible to subject the recovered organic layer directly to the subsequent reaction step.
As mentioned above, it is possible in the present invention that the hydroxyl group substitution product can be manufactured by reaction of the alcohol with sulfuryl fluoride in the presence of the organic base and nucleophile (Inventive Aspect 1).
Among Inventive Aspect 1, the following material combination is preferred (Inventive Aspect 2): the raw substrate is an optically active alcohol in which one of three substituent groups is a hydrogen atom and the other two of three substituent groups are different in kind from each other and are each independently selected from an alkyl group, a substituted alkyl group, a formyl group, an alkylcarbonyl group, a substituted alkylcarbonyl group, an arylcarbonyl group, a substituted arylcarbonyl group, an alkoxycarbonyl group, a substituted alkoxycarbonyl group, an aminocarbonyl group, an alkylaminocarbonyl group, a substituted alkylaminocarbonyl group, an arylaminocarbonyl group, a substituted arylaminocarbonyl group and a cyano group; and the nucleophile constituting species X is a halogen atom such as chlorine, bromine or iodine, an azide group, a formyloxy group, an alkylcarbonyloxy group, a substituted alkylcarbonyloxy group, an arylcarbonyloxy group or a substituted arylcarbonyloxy group. The combination of the raw substrate and the nucleophile according to this aspect is advantageous in that: the desired reaction proceeds very favorably; and the obtained optically active hydroxyl group substitution product is very important as an intermediate for pharmaceutical and agricultural chemicals.
The following material combination is particularly preferred (Inventive Aspect 3) among Inventive Aspect 2: the raw substrate is an optically active α-hydroxyester in which one of three subsitutent groups is a hydrogen atom, another one of three substituent groups is an alkoxycarbonyl group or a substituted alkoxycarbonyl group and the other one of three substituent groups is an alkyl group or a substituted alkyl group; and the nucleophile constituting species X is a halogen atom such as chlorine, bromine or iodine or an azide group. The combination of the raw substrate and the nucleophile according to this aspect is advantageous in that: the desired reaction proceeds extremely favorably; and the obtained optically active α-hydroxyl group substitution ester is extremely important as an intermediate for pharmaceutical and agricultural chemicals.
The following material combination is also particularly preferred (Inventive Aspect 4) among Inventive Aspect 2: the raw substrate is an optically active 4-hydroxyproline in which a secondary amino group and an carboxyl group are protected by protecting groups, respectively; and the nucleophile constituting species X is a halogen atom such as chlorine, bromine or iodine or an azide group. The combination of the raw substrate and the nucleophile according to this aspect is also advantageous in that: the desired reaction proceeds extremely favorably; and the obtained optically active 4-hydroxyl group substitution proline is extremely important as an intermediate for pharmaceutical and agricultural chemicals.
The present invention will be described in more detail below by way of the following examples. It should be noted that these examples are illustrative and are not intended to limit the present invention thereto. In the following description, the abbreviations “Me”, “Et”, “Boc” and “Ac” refer to methyl, ethyl, tert-butoxycarbonyl and acetyl, respectively.
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 4.73 g (40.0 mmol, 1.00 eq) of optically active α-hydroxyester of the following formula (S-configuration, 98% ee or higher):
40 mL (1.00 M) of acetonitrile, 4.65 g (36.0 mmol, 0.90 eq) of diisopropylethylamine and 11.6 g (36.0 mmol, 0.90 eq) of tetrabutylammonium bromide. Then, 8.16 g (80.0 mmol, 2.00 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours and 50 minutes under ice cooling conditions. A part of the reaction mixture solution was diluted with ethyl acetate, washed with water, and then, analyzed by gas chromatography.
It was confirmed by the analytical results that: the conversion rate was 81%; the area percentage of optically active α-hydroxyl group substitution ester of the following formula (R-configuration):
was 73.8%; and the area percentage of fluorinated compound of the following formula:
was 2.3%.
The area percentage ratio of the optically active α-hydroxyl group substitution ester and the fluorinated compound was 97:3. The optical purity of the optically active α-hydroxyl group substitution ester (R-configuration) was 91.8% ee. The 1H-NMR data of the optically active α-hydroxyl group substitution ester are indicated below. (There was almost no quaternary ammonium salt contained.)
1H-NMR [reference material: (CH3)4Si, deuterium solvent: CDCl3] δ ppm; 1.30 (t, 7.2 Hz, 3H), 1.83 (d, 6.8 Hz, 3H), 4.23 (q, 7.2 Hz, 2H), 4.36 (q, 6.8 Hz, 1H).
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 4.73 g (40.0 mmol, 1.00 eq) of optically active α-hydroxyester of the following formula (S-configuration, 98% ee or higher):
40 mL (1.00 M) of acetonitrile, 4.86 g (48.0 mmol, 1.20 eq) of triethylamine, 6.16 g (40.0 mmol, 1.00 eq) of tetramethylammonium bromide and 13.3 g (41.3 mmol, 1.03 eq) of tetrabutylammonium bromide. Then, 8.16 g (80.0 mmol, 2.00 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours under ice cooling conditions. A part of the reaction mixture solution was diluted with ethyl acetate, passed through a short column of silica (for removal of origin component), and then, analyzed by gas chromatography.
It confirmed by the analytical results that: the conversion rate of the reaction was 100%; the area percentage of optically active α-hydroxyl group substitution ester of the following formula (R-configuration):
was 94.5%; and the area percentage of fluorinated compound of the following formula:
was 1.8%. The area percentage ratio of the optically active α-hydroxyl group substitution ester and the fluorinated compound was 98:2. The optical purity of the optically active α-hydroxyl group substitution ester (R-configuration) was 88.3% ee.
The 1H-NMR data of the optically active α-hydroxyl group substitution ester was the same as that of Example 1. (There was almost no quaternary ammonium salt contained.)
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 5.00 g (20.4 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
20 mL (1.02 M) of acetonitrile, 4.13 g (40.8 mmol, 2.00 eq) of triethylamine and 13.1 g (40.6 mmol, 1.99 eq) of tetrabutylammonium bromide. Then, 4.16 g (40.8 mmol, 2.00 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours and 30 minutes under ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was concentrated under a reduced pressure to about one-third volume, diluted with 100 mL of toluene and washed six times with 50 mL of water. The organic layer was recovered, concentrated under a reduced pressure and subjected to vacuum drying, thereby yielding 6.40 g of a crude product of optically active 4-hydroxyl group substitution proline of the following formula (S-configuration at 2-position/S-configuration at 4-position):
The yield of the product was quantitative.
It was confirmed by 1H-NMR and 19F-NMR analysis of the crude product that no fluorinated compound of the following formula:
was contained (less than 3 mol %). The 1H-NMR data of the optically active 4-hydroxyl group substitution proline are indicated below. (There was almost no quaternary ammonium salt contained.)
1H-NMR [reference material: (CH3)4Si, deuterium solvent: CDCl3] δ ppm; 1.42 (s, part of 9H), 1.47 (s, part of 9H), 2.42 (m, 1H), 2.84 (m, 1H), 3.73 (m, 1H), 3.77 (s, 3H), 4.06 (m, 1H), 4.20-4.50 (m, 2H).
The optically active 4-hydroxyl group substitution proline of the above formula can be converted, through an azide compound of the following formula (S-configuration at 2-position/R-configuration at 4-position):
to an amino compound of the following formula (S-configuration at 2-position/R-configuration at 4-position):
with reference to Patent Document 1, Journal of Medicinal Chemistry (U.S.), 2006, Vol. 49, P. 307-317 and the like.
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 49.1 g (200 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
195 mL (1.03 M) of toluene, 200 mL (1.00 M) of acetonitrile, 40.5 g (400 mmol, 2.00 eq) of triethylamine and 133 g (413 mmol, 2.07 eq) of tetrabutylammonium bromide. Then, 40.8 g (400 mmol, 2.00 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under salt-ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours under salt-ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was washed with 300 mL of water. The organic layer was recovered, concentrated under a reduced pressure and subjected to vacuum drying, thereby yielding 145 g of a crude product of optically active 4-hydroxyl group substitution proline of the following formula (S-configuration at 2-position/S-configuration at 4-position):
It was confirmed by 1H-NMR and 19F-NMR analysis of the crude product that no fluorinated compound of the following formula:
was contained (less than 3 mol %).
It was also confirmed that there was a considerable amount of quaternary ammonium salt contained in the crude product (the mole ratio of the target compound and the quaternary ammonium salt was 53:47). To 68.4 g (estimated as 94.3 mmol) of the crude product, 51 mL (1.85 M) of toluene and 120 mL (0.786 M) of n-heptane were added. The resulting solution was stirred for 2 hours at room temperature, followed by filtering crystalline matter (quaternary ammonium salt) out of the solution. The filtration residue was washed with a small amount of n-heptane. The thus-obtained filtrate was concentrated under a reduced pressure and subjected to vacuum drying, thereby recovering 28.4 g of a purified product of optically active 4-hydroxyl group substitution proline of the above formula. It was confirmed by 1H-NMR analysis of the purified product that the quaternary ammonium salt had been totally removed (less than 3 mol %). The yield of the product was 98%. The 1H-NMR data of the optically active 4-hydroxyl group substitution proline was the same as that of Example 3.
To 11.8 g (38.3 mmol, 1.00 eq) of the purified product of the optically active 4-hydroxyl group substitution proline of the above formula, 77 mL (0.497 M) of N,N-dimethylformamide and 2.74 g (42.1 mmol, 1.10 eq) of sodium azide were added. The resulting reaction mixture solution was stirred for 2 days at room temperature. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was diluted with 200 mL of ethyl acetate and washed three times with 100 mL of water. The organic layer was recovered, concentrated under a reduced pressure and subjected to vacuum drying, thereby yielding 12.5 g of a crude product of an azide compound of the following formula (S-configuration at 2-position/R-configuration at 4-position):
It was confirmed by 1H-NMR analysis (quantitative analysis) of the crude product that 9.16 g of the target compound was contained (there was a considerable amount of N,N-dimethylformamide contained). The yield of the product was 89%. The 1H-NMR data of the azide compound are indicated below. (No 4-position epimer (S-configuration at 4-position) was contained (less than 3 mol %).)
1H-NMR [reference material: (CH3)4Si, deuterium solvent: CDCl3] δ ppm; 1.42 (s, part of 9H), 1.47 (s, part of 9H), 2.18 (m, 1H), 2.33 (m, 1H), 3.42-3.84 (m, 2H), 3.74 (s, 3H), 4.20 (m, 1H), 4.38 (m, 1H).
To 12.5 g (estimated as 33.9 mmol, 1.00 eq) of the crude product of the azide compound of the above formula, 34 mL (0.997 M) of methanol and 2.89 g (50% water content, 0.679 mmol, 0.02 eq) of 5% palladium/activated carbon were added. The resulting reaction mixture solution was stirred for one night at room temperature while setting the pressure of hydrogen gas (H2) at 0.15 MPa. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was subjected to Celite filtration. The filtrate was admixed with 3.53 g (33.9 mmol, 1.00 eq) of 35% hydrochloric acid, stirred for 15 minutes at room temperature, concentrated under a reduced pressure, subjected to azeotropic dehydration twice with 100 mL of toluene, and then, subjected to vacuum drying. With this, 11.1 g of a crude product of hydrochloride of amino compound of the following formula (S-configuration at 2-position/R-configuration at 4-position):
was yielded (There was contained a small amount of N,N-dimethylformamide and toluene). The yield of the product was quantitative. To the whole (estimated as 33.9 mmol) of the crude product of the hydrochloride, 30 mL (1.13 M) of ethyl acetate, 30 mL (1.13 M) of n-hexane and 6 mL (5.65 M) of isopropanol were added. The crude product of the hydrochloride was dissolved into the solvent by heating. The resulting solution was cooled down to room temperature, followed by filtering crystalline precipitate out of the solution. The filtration residue was washed with a small amount of n-hexane and subjected to vacuum drying, thereby recovering 3.95 g of a purified product of hydrochloride of amino compound of the above formula.
The gas chromatographic purity of the purified product (free base) was 99.2%. The yield of the product until recrystallization was 41%. (The recrystallization conditions were not optimized.) The 1H-NMR data of the hydrochloride and free base of the amino compound are indicated below.
Hydrochloride: 1H-NMR [reference material: (CH3)4Si, deuterium solvent: CD3OD] δ ppm; 1.42 (s, part of 9H), 1.47 (s, part of 9H), 2.39 (m, 2H), 3.54 (m, 1H), 3.75 (s, part of 3H), 3.76 (s, part of 3H), 3.80 (m, 1H), 3.93 (m, 1H), 4.45 (m, 1H). (The attributions of the NH2 and HCl proton peaks were not identifiable.)
Free base: 1H-NMR [reference material: (CH3)4Si, deuterium solvent: CDCl3] δ ppm; 1.41 (s, part of 9H), 1.46 (s, part of 9H), 1.91-2.19 (m, 2H), 3.06-3.24 (m, 1H), 3.65-3.76 (m, 2H), 3.73 (s, 3H), 4.39 (m, 1H). (The attribution of the NH2 proton peak was not identifiable.)
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 736 mg (3.00 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
3 mL (1.00 M) of acetonitrile, 610 mg (6.03 mmol, 2.01 eq) of triethylamine and 1.71 g (6.01 mmol, 2.00 eq) of tetrabutylammonium azide. Then, 610 mg (5.98 mmol, 1.99 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours and 45 minutes under ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was diluted with ethyl acetate, washed five times with saturated sodium chloride solution. The organic layer was recovered, concentrated under a reduced pressure and subjected to vacuum drying. The residue was treated with a short column of silica (ethyl acetate:n-hexane=1:1), thereby yielding 600 mg of a crude product of optically active 4-hydroxyl group substitution proline of the following formula (S-configuration at 2-position/S-configuration at 4-position):
It was confirmed by 1H-NMR and 19F-NMR analysis of the crude product that fluorinated compound of the following formula:
was contained. The mole ratio of the optically active 4-hydroxyl group substitution proline and the fluorinated compound was 57:43. The yield of the optically active 4-hydroxyl group substitution proline was thus 44%. It was also confirmed that no 4-position diastereomer was contained in the optically active 4-hydroxyl group substitution proline.
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 736 mg (3.00 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
3 mL (1.00 M) of acetonitrile, 610 mg (6.03 mmol, 2.01 eq) of triethylamine, 1.71 g (6.01 mmol, 2.00 eq) of tetrabutylammonium azide and 390 mg (6.00 mmol, 2.00 eq) of sodium azide. Then, 610 mg (5.98 mmol, 1.99 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 1 hour under ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
Further, it was confirmed by gas chromatography of the reaction mixture solution that the area percentage ratio of the optically active 4-hydroxyl group substitution proline of the following formula (S-configuration at 2-position/S-configuration at 4-position):
and the fluorinated compound of the following formula:
was 84:16. It was also confirmed that no 4-position diastereomer was contained in the optically active 4-hydroxyl group substitution proline.
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 736 mg (3.00 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
3 mL (1.00 M) of acetonitrile, 610 mg (6.03 mmol, 2.01 eq) of triethylamine and 1.80 g (5.99 mmol, 2.00 eq) of tetrabutylammonium thiocyanate. Then, 610 mg (5.98 mmol, 1.99 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours and 40 minutes under ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
Further, it was confirmed by gas chromatography of the reaction mixture solution that the area percentage ratio of the optically active 4-hydroxyl group substitution proline of the following formula:
and the fluorinated compound of the following formula:
was 70:30. It was also confirmed that there was 4-position diastereomer contained in the optically active 4-hydroxyl group substitution proline. The diastereomer ratio (S-configuration at 2-position/S-configuration at 4-position (estimate):S-configuration at 2-position/R-configuration at 4-position (estimate)) was 79:21.
Into a pressure-proof reaction vessel of stainless steel (SUS) were placed 736 mg (3.00 mmol, 1.00 eq) of optically active 4-hydroxyproline of the following formula (S-configuration at 2-position/R-configuration at 4-position, 98% ee or higher, 98% de or higher):
3 mL (1.00 M) of acetonitrile, 610 mg (6.03 mmol, 2.01 eq) of triethylamine and 1.81 g (6.00 mmol, 2.00 eq) of tetrabutylammonium acetate. Then, 610 mg (5.98 mmol, 1.99 eq) of sulfuryl fluoride was blown from a cylinder into the reaction vessel under ice cooling conditions. The resulting reaction mixture solution was stirred for 2 hours and 30 minutes under ice cooling conditions. It was confirmed by 1H-NMR analysis of the reaction mixture solution that the conversion rate of the reaction was 100%.
The thus-obtained reaction terminated liquid was diluted with ethyl acetate and washed five times with water. The organic layer was recovered, concentrated under a reduced pressure and subjected to vacuum drying. The residue was extracted by stirring with n-hexane (for filtration separation of solid tetrabutylammonium salt), thereby yielding 572 mg of a crude product of optically active 4-hydroxyl group substitution proline of the following formula:
It was confirmed by gas chromatography of the crude product that fluorinated compound of the following formula:
was contained. The area percentage ratio of the optically active 4-hydroxyl group substitution proline and the fluorinated compound was 98:2.
Thus, the yield of the optically active 4-hydroxyl group substitution proline was 65% on the assumption that the area percentage ratio corresponded to the mole ratio. It was also confirmed that there was 4-position diastereomer contained in the optically active 4-hydroxyl group substitution proline. The diastereomer ratio (S-configuration at 2-position/S-configuration at 4-position:S-configuration at 2-position/R-configuration at 4-position) was 72:28.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-321502 | Dec 2008 | JP | national |
| 2009-225952 | Sep 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/070904 | 12/15/2009 | WO | 00 | 6/16/2011 |
