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US 3,941,828 AGranted
Process for the preparation of cyclic ketones
AssigneeFirmenich SA
InventorGeorge Hermann Buchi
Life of this patent
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Abstract
New process for the preparation of cyclic ketones possessing interesting organoleptic properties and including methyl 2-(cis-pent-2-enyl)-3-oxo-cyclopentylacetate and 3-methyl-2-(cis-pent-2-enyl)-cyclopent-2-enone, better known in the perfume industry as cis-methyl jasmonate and cis-jasmone respectively.
Claims10
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.
7 more elements
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.
Dependencies are inferred from the claim text.