Claims
- 1. A process for the preparation of cyclic ketones having the formula ##SPC8##
- wherein the symbol (=R.sup.1) represents an alkylidene radical containing one to five carbon atoms, R indicates a lower alkyl radical having a linear or a branched chain, and n stands for the integer 0, 1, 3 or 4, which comprises:
- a. alkylating cyclohexane-1,3-dione by treating it with an alkyne halide of formula
- X--(CH.sub.2).sub.n --C(.tbd.R.sup.2) II
- wherein X represents a halogen, (.tbd.R.sup.2) represents an alkylidyne radical containing one to five carbon atoms, and n stands for the integer 0, 1, 3 or 4;
- b. reacting the obtained 2-alkynyl-cyclohexane-1,3-dione with a halogenating agent;
- c. treating the resulting 2-halo-2-alkynyl-cyclohexane-1,3-dione in a solvent selected from the group of methyl-, ethyl-, and isopropyl alcohol, tetrahydrofurane, dioxane, dimethylformamide, anhydrous xylene and mesitylene, with a mineral or an organic base selected from the group of trimethylamine, triethylamine, N,N-diisopropylethylamine, pyridine, .alpha.-, .beta.-, or .gamma.- collidine, ethyl pyridine, picoline, lutidine, alkali metal hydroxides, and alkali metal carbonates and bicarbonates, at a temperature from about 15.degree. to about 200.degree.C, for obtaining a 2-alkynyl-cyclopent-2-enone;
- d. adding on to the cyclic double bond of the obtained ketone a dialkyl malonate in the presence of a base catalyst;
- e. hydrolysing and subsequently decarboxylating the dialkyl 2-alkynyl-3-oxo-cyclopentyl malonate, obtained according to (d), by treating it successively with a base and an acid;
- f. esterifying the 2-alkynyl-3-oxo-cyclopentyl acetic acid obtained, and
- g. partially hydrogenating the resulting ester in the presence of a partially poisoned hydrogenation catalyst.
- 2. A process according to claim 1, wherein the halogenating reagent for preparing the 2-halo-2-alkynyl-cylohexane-1,3-dione is a compound acting as a positive halogen donor.
- 3. A process according to claim 1, wherein the positive halogen donor is tert.-butyl hypochlorite.
- 4. A process according to claim 1, wherein dimethyl malonate is added on to the ring double bond of 2-alkynyl-cyclopent-2-enone in the presence of sodium methoxide.
- 5. A process according to claim 1, which comprises:
- a. alkylating cyclohexane-1, 3-dione by treating it with 1-bromo-pent-2-yne in an aqueous alkaline medium and at a temperature comprised in between about 10.degree. and about 60.degree.C;
- b. treating a suspension of the resulting 2-(pen-2-ynyl)-cyclohexane-1, 3-dione in chloroform with tert.-butyl hypochlorite at a temperature comprised in between about -15.degree. and -20.degree.C;
- c. treating a solution of the resulting 2-chloro-2-(pent-2-ynyl)-cyclohexane-1, 3-dione in xylene with anhydrous sodium carbonate, at a temperature from about 15.degree. to about 200.degree.C, to yield 2-(pent-2-ynyl)-cyclopent-2-enone;
- d. adding dimethyl malonate on to the ring double bond of the resulting ketone at a temperature of about -5.degree.C and in the presence of sodium methoxide;
- e. hydrolysing the resulting 3-dimethoxycarbonylmalonyl-2-(pent-2-ynyl)-cyclopentanone in an aqueous alkaline medium and at room temperature, and subsequently decarboxylating the acid thus obtained by means of sulfuric acid to yield 2-(pent-2-ynyl)-3-oxo-cyclopentyl acetic acid;
- f. esterifying said acid by means of methyl alcohol in the presence of a mineral acid, and
- g. hydrogenating the methyl ester in the presence of a partially poisoned hydrogenation catalyst to yield methyl 2-(cis-pent-2-enyl)-3-oxo-cyclopentyl acetate.
- 6. A process for the preparation of compounds of formula ##SPC9##
- wherein R.sup.3 represents either a lower alkyl radical comprising 1 to 6 carbon atoms, or an alkenyl or an alkynyl radical comprising 2 to 6 carbon atoms, and R.sup.4 represents a lower alkyl radical or a hydrogen atom, which comprises treating a compound of formula ##SPC10##
- wherein X represents a halogen atom, and R.sup.3 and R.sup.4 have the same significance as that given above, in a solvent selected from the group of methyl-, ethyl-, and isopropyl alcohol, tetrahydrofurane, dioxane, dimethylformamide, and anhydrous xylene and mesitylene, with a mineral or an organic base selected from the group of trimethylamine, triethylamine, N,N-diisopropylethylamine, pyridine, .alpha.-, .beta.-, or .gamma.-collidine, ethyl pyridine, picoline, lutidine, alkali metal hydroxides, and alkali metal carbonates and bicarbonates, at a temperature from about 15.degree. to about 200.degree.C.
- 7. A process according to claim 6, wherein there is used a 4-methyl-2-halo-2-(cis-pent-2-enyl)-cyclohexane-1,3-dione as starting material to yield 3-methyl-2-(cis-pent-2-enyl)-cyclopent-2-enone.
- 8. A process according to claim 6, wherein there is used a 4-methyl-2-halo-2-pentyl-cyclohexane-1,3-dione as starting material to yield 3-methyl-2-pentyl-cyclopent-2-enone.
- 9. A process according to claim 6, wherein there is used a 4-methyl-2-halo-2-(pent-2-ynyl)-cyclohexane-1,3-dione as starting material to yield 3-methyl-2-(pent-2-ynyl)-cyclopent-2-enone.
- 10. A process according to claim 9, wherein the obtained 3-methyl-2-(pent-2-ynyl)-cyclopent-2-enone is partially hydrogenated in the presence of a partially poisoned hydrogenation catalyst to afford 3-methyl-2-(cis-pent-2-enyl)-cyclopent-2-enone.
Priority Claims (2)
Number |
Date |
Country |
Kind |
18303/70 |
Dec 1970 |
CH |
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16493/71 |
Nov 1971 |
CH |
|
Parent Case Info
This is a continuation of application Ser. No. 201,168, filed Nov. 22, 1971 now abandoned.
Non-Patent Literature Citations (1)
Entry |
kende, Organic Reactions, 11, pp. 286-288, (1960). |
Continuations (1)
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Number |
Date |
Country |
Parent |
201168 |
Nov 1971 |
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