Patent GB-1041023-A (GB)
Title: Cyclopentanonylacetic acid derivatives and perfume compositions containing them
IPC: C11B9/00
Filed: 1963-02-22
Abstract: The invention comprises compounds of the formula <FORM:1041023/C2/1> wherein one of the symbols R1 and R2 represents hydrogen and the other an unsubstituted alkenyl radical having 5 carbon atoms and R represents methyl or ethyl.  The alkenyl radical can be a cis- or trans-1-penten-1-yl, 2-penten-1-yl, 3-penten-1-yl, 4-penten-1-yl, or 3-methyl-2-buten-1-yl radical. The compounds of the above formula in which R1 or R2 is a -CH2-CH = CH-C2H5 or -CH2-CH = C(CH3)2 group are obtained by condensing a methyl or ethyl 3-oxo-cyclopentylacetate with a cyclic secondary amine in order to obtain a mixture of two isomeric enamines, subjecting this mixture to the action of an alkenyl halide having 5 carbon atoms, e.g. the cis- and transisomers of 1-bromo-2-pentene or 1-bromo-3-methyl-2-butene, and hydrolysing the product to a mixture of methyl or ethyl 2- and 4-(2-alkenyl)-3-oxo-cyclopentylacetates, which may be separated if desired.  Alternatively the mixture of enamines may be heated with a 1-halo-2-alkyne having five carbon atoms, e.g. 1-bromo-2-pentyne, the product hydrolysed by means of an acid to a mixture of methyl or ethyl 2- and 4-(2-alkynyl)-3-oxo-cyclopentyl acetates, the mixture or separated isomers subjected to catalytic partial hydrogenation in the presence of a palladium catalyst to obtain the desired product. These compounds are also obtained by mono-decarboxylating a methyl or ethyl 2,4-dicarbalkoxy - 3 - oxo - cyclopentyl acetate by means of a weak aqueous acid, esterifying the resulting mixture of 2- and 4-carboxy-3-oxo-cyclopentylacetic acids to form the acetates, condensing in the presence of a basic condensing agent with a 1-alken-3-ol having 5 carbon atoms to obtain a mixture of methyl or ethyl 2- and 4 - (2 - trans - alkenyl) - 3 - oxo - cyclopentyl acetates, which may be separated.  The compounds of the above formula in which R2 is hydrogen and R1 is a pentyl group having its double bond in th 3,4- or 4,5-position are obtained by condensing an appropriate organo-magnesium compound, for example one of the formula XMg-CH2-CH2-CH = CH-CH3 or XMg-CH2-CH2-CH2-CH = CH2, where X is a halogen, with a lower alkyl enol ether of cyclopentan-1,2-dione, and hydrolysing the resulting metal-organic compound in order to obtain a 2-alkenyl-2-cyclopentene-1-one, adding bis-tetrahydropyanyl malonate to the cyclic double bond of this ketone in the presence of an alkaline catalyst in order to obtain a bistetrahydropyranyl 2-alkenyl-3-oxo-cyclopentyl malonate, hydrolysing and decarboxylating this malonate, and esterifying the resulting 2-(3- or 4-alken-1-yl)-3-oxo-cyclopentyl acetic acid to convert it into its methyl or ethyl ester.ALSO:A perfume composition comprises olefactory materials suitable for cosmetic use and including in addition from 0.1 to 9% by weight of said materials of at least one racemic compound of the formula <FORM:1041023/A5-A6/1> wherein one of the symbols R1 and R2 represents hydrogen and the other an unsubstituted alkenyl radical having 5 carbon atoms and R represents a methyl or ethyl radical.  Examples include typical olefactory materials used in perfume compositions.