Claims
- 1. A process for the preparation of an oxirane of the formula ##STR11## in which Y represents chlorine
- X represents oxygen and
- Z represents hydrogen,
- which consists contacting, without previous isolation, dimethyl sulphide with dimethyl sulphate in the presence of toluene and contacting the resultant trimethylsulphonium methyl sulphate of the formula
- (CH.sub.3).sub.3 S.sym.CH.sub.3 SO.sub.4.sup..crclbar. (II)
- with a ketone of the formula ##STR12## in which X,Y and Z have the meanings indicated above, in the presence of potassium hydroxide powder and in the presence of toluene at a temperature between 10.degree. C. and 40.degree. C. wherein 1.0 to 1.5 moles of said dimethylsulfate, 1.0 to 1.6 moles of said dimethyl sulphide and 1.5 to 2.0 mols of said potassium hydroxide are employed per mole of said ketone and no water is added to the reaction mixture.
- 2. A process according to claim 1, wherein said process is carried out under normal pressure.
- 3. A process according to claim 1, wherein said process is carried out under elevated pressure.
- 4. A process according to claim 1, wherein said process is carried out under reduced pressure.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 3315619 |
Apr 1983 |
DEX |
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Parent Case Info
This is a continuation of application Ser. No. 603,478, filed Apr. 24, 1984, now abandoned.
The present invention relates to a new process for the preparation of known oxiranes which can be used as intermediates for the synthesis of compounds having plant-growth regulating and fungicidal activity.
It has already been disclosed that oxiranes can be prepared by reacting dimethyl sulphide and dimethyl sulphate and then reacting the trimethylsulphonium methyl sulphate, which is formed thereby as an intermediate, with carbonyl compounds in the presence of an inert organic solvent and in the presence of a strong base, such as butyl-lithium, sodium hydride, sodium amide, potassium tert.-butylate, sodium methylate or sodium ethylate (compare J. Amer. Chem. Soc. 87, 1353-1364 (1965) and Ber. 96, 1881 (1963)). Thus, for example, 2-(4-chlorophenoxymethyl)-2-tert.-butyloxyirane can be prepared by reacting trimethylsulphonium methyl sulphate, prepared from dimethyl sulphide and dimethyl sulphate, in situ with 1-(4-chlorophenoxy)-3,3-diemthyl-2-butanone in acetonitrile in the presence of sodium methylate (compare EP-OS (European Published Specification) No. 40,345). The yields in this process are good. However, it is a disadvantage that all the bases used need to be specially prepared and are difficult to manipulate since they are sensitive to moisture and some of them are flammable.
It has also been disclosed that oxiranes are obtained when dimethyl sulphide is treated with dimethyl sulphate, and the trimethylsulphonium methyl sulphate thereby produced is reacted with carbonyl compounds in the presence of concentrated aqueous sodium hydroxide solution and an organic solvent which is poorly miscible with water and in the presence of a phase-transfer catalyst (compare Angew. Chem. 85, 867-868 (1973) and J. Org. Chem. 34, 2133 (1969)). However, hitherto only aldehydes have been converted into oxiranes using this process. In addition, the presence of a phase-transfer catalyst is always necessary in the system which consists of two liquid phases.
It has now been found that the known oxiranes of the formula ##STR2## in which Y represents chlorine or phenyl,
It must be denoted extremely surprising that oxiranes of the formula (I) can be prepared by the process according to the invention in higher yields than by the processes hitherto known. Moreover, on the basis of the known state of the art, it had to be assumed that the presence of a phase-transfer catalyst would be necessary for this type of reaction of ketones which, of course, are generally less reactive than the corresponding aldehydes. However, this is not necessary, in contrast to expectation. The reaction takes place without problems even in the absence of a catalyst, although it is taking place in a system comprising a solid and a liquid phase. It is also surprising that the reaction according to the invention can be carried out without difficulty using sodium hydroxide or potassium hydroxide while the same reaction provides unsatisfactory results when powdered lithium hydroxide is used as the base.
The process according to the invention is distinguished by a number of advantages. Thus, the bases which can be used are also available on an industrial scale, are straightforward to manipulate and are not flammable. Furthermore, the oxiranes of the formula (I) are accessible in very high yields by this means.
The oxiranes which can be prepared according to the invention are defined by the formula (I). In this formula, X represents oxygen or the CH.sub.2 group. Y represents chlorine or phenyl and Z preferably represents hydrogen, fluorine or chlorine.
When 1-(4-chlorophenoxy)-3,3-dimethyl-2-butanone is used as the starting material and potassium hydroxide powder is used as the base in the process according to the invention, then the course of the reaction can be illustrated by the diagram below: ##STR4##
The ketones necessary as starting materials in the process according to the invention are defined by the formula (III). In this formula, Y represents chlorine or phenyl. X represents oxygen or the CH.sub.2 group and Z preferably represents hydrogen, fluorine or chlorine.
The ketones of the formula (III) are known (compare German Patent Specification No. 2,201,063, DE-OS (German Published Specification) No. 2,705,678 and DE-OS (German Published Specification) No. 2,737,489).
The trimethylsulphonium methyl sulphate of the formula (II) which is also necessary as a starting material in the process according to the invention is likewise known (compare Heterocycles 8, 397 (1977)). It is employed in the above reaction in the freshly prepared state by producing it in situ by reaction of dimethyl sulphide with dimethyl sulphate.
The bases used in the process according to the invention are powdered potassium hydroxide or powdered sodium hydroxide.
All inert organic solvents can be used as the diluent for the process according to the invention, both for the preparation of the trimethylsulphonium methyl sulphate and for the subsequent reaction of the material with a ketone of the formula (III). Suitable and preferable are nitriles, such as acetonitrile, as well as polar solvents, such as dimethyl sulphoxide, also aliphatic or aromatic hydrocarbons, such as hexane, benzene, toluene or xylene, and finally alcohols, such as tert.-butanol and isopropanol and furthermore N-methylpyrrolidone.
On carrying out the process according to the invention, the reaction temperatures can be varied within a certain range. In general, both for the preparation of the trimethylsulphonium methyl sulphate and for its subsequent reaction with a ketone of the formula (III), temperatures between 0.degree. C. and 60.degree. C., preferably between 10.degree. C. and 40.degree. C., are used.
The process according to the invention is generally carried out under normal pressure. However, it is also possible to carry it out under elevated or reduced pressure.
On carrying out the process according to the invention, the amounts of the components in the reaction are generally selected such that 1.0 to 2.0 mole, preferably 1.0 to 1.5 mole, of dimethyl sulphate, 1.0 to 2.2 mole, preferably 1.0 to 1.6 mole, of dimethyl sulphide and 1.0 to 4.0 mole, preferably 1.5 to 2.0 mole, of potassium hydroxide or sodium hydroxide are employed for 1 mole of ketone of the formula (III).
The specific procedure for the process according to the invention is such that dimethyl sulphide and dimethyl sulphate are mixed in a solvent, then a solution of a ketone of the formula (III) in an organic solvent is added to this solution, and the particular required amount of base is subsequently added. Working up is carried out by customary methods. In general, the procedure is such that first the solvent is removed in vacuo, then oxidising agents, such as aqueous hydrogen peroxide solution, dilute aqueous sodium hypochlorite or potassium hypochlorite solution, or together with a mixture of water and an organic solvent which is poorly miscible with water, are added to the residue remaining, and the organic phase is separated off, washed and evaporated after previous drying if necessary. The product resulting thereby can be distilled under reduced pressure for further purification.
The oxiranes of the formula (I) which can be prepared by the process according to the invention are valuable starting materials for the synthesis of 1-hydroxy-ethylazole derivatives which have outstanding plant-growth regulating and fungicidal properties (compare EP-OS (European Published Specification) No. 40,345).
Thus, for example, 2-(4-chlorophenoxymethyl)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-2-butanol of the formula ##STR5## can be prepared by reacting 2-(4-chlorophenoxymethyl)-2-tert.-butyloxirane with 1,2,4-triazole in the presence of potassium hydroxide. This synthesis can be illustrated by the formulae below: ##STR6##
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EPX |
Non-Patent Literature Citations (7)
| Entry |
| Bogdanowicz et al., Tetrahedron Letters, No. 10, (1972), pp. 887-890. |
| Borredon et al., Tetrahedron Letters, vol. 23(50), 1982, pp. 5283-5286, (English translation). |
| T. Kutsuma et al., Heterocycles, vol. 8, (1977), pp. 397-401. |
| V. Franzen et al., Berichte, vol. 96, (1963), pp. 1881-1890. |
| E. J. Corey et al., J.A.C.S., vol. 87(6), (1965), pp. 1353-1364. |
| E. J. Corey et al., J.A.C.S., vol. 84(19), (1962), pp. 3782-3783. |
| Journal of the American Chemical Society, Band 95, No. 16, Aug. 8, 1973, Seiten 5311-5321, Columbus, Ohio, U.S.: B. M. Trost et al. |
Continuations (1)
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Number |
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| Parent |
603478 |
Apr 1984 |
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Patent Grant
4960911
