US 2003/0212281 A1 · Heptanonic acid and furanone compounds and compositions

Abstract

A natural inexpensive acyclic monoterpene ketone (dihydrotagetone) of formula (4), isolated from the oil of Tagetes sp., was smoothly oxidized with meta-periodate/potassium permanganate into 2,6-dimethyl-4-oxo-heptanoic acid of formula (3), the reduction of 3 with metal hydride such as sodium borohydride or lithium aluminium hydride provided 4-hydroxyacid of formula (2) which on without isolation undergone lactonisation in acidic medium furnished two chiral centered 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone of formula (1) as an analogue of whisky lactone 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1a) responsible for high quality of alcoholic beverage (whisky, wine, brandy and scotch), in addition, coconut flavoured 5-butyl-4-methyl-4,5-dihydro-2(3H)-furanone of formula (1) is also as an analogue of coconut aldehyde (γ-nonalactone, F.E.M.A. No. 2751) of formula (1b) which is responsible for flavouring a wide range of food stuffs including baked goods and confectionery.

A novel method for converting dihydrotagetone, a bifuctional acyclic monoterpene ketone, isolated from the plant species of Tagetes into a coconut flavoured two chiral centered compound 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone as a novel analogue of natural whisky lactone and coconut aldehyde of the formula (1)

4
the said method comprising
a. adsorbing Tagetes minuta oil on an adsorbent selected from but not limited to alumina and silica gel;
b. loading adsorbent obtained from step (a) on a soxhlet extractor and washing with a non polar solvent (cold percolation) selected from but not limited to petroleum ether and hexane for removing the non polar constituents;
c. isolating the dihydrotagetone rich fractions using hot hexane percolation with increasing percentage of ethylacetate starting from 0.2 upto 5%;
d. concentrating the above separated fractions under reduced pressure to obtain a dihydrotagetone rich concentrate;
e. loading above concentrate on alumina or silica gel column and eluting the column with a non polar solvent selected from but not limited to hexane and petroleum ether;
f. eluting the column further with increasing percentage of ethyl acetate upto 5% in hexane;
g. concentrating the resulting hexane-ethylacetate fractions under reduced pressure to obtain dihydrotagetone of formula (4) in 99% or more purity;
h. providing dihydrotagetone of formula (4) in organic solvent selected from the group consisting of ether selected from but not limited to tetrahydrofuran, dimethoxyethane and dioxane, alcohol selected from but not limited to butanol and t-butyl alcohol, ketone selected from but not limited to acetone and methyl ethyl ketone;
i. oxidising dihydrotagetone of formula (4) in the presence of an oxidizing reagent selected from but not limited to sodium meta-periodate, potassium meta-periodate and ruthenium tertaoxide in the range of 2 to 8 times mole of dihydrotagetone of formula (4) and a co-oxidizing agent selected from but not limited to potassium permanganate and sodium permanganate in the range of 0.1 to 0.6 times mole of dihydrotagetone (starting material) of formula (4);
j. adding a base selected from the group consisting of but not limited to sodium carbonate, sodium bicarbonate, potassium carbonate, lithium carbonate and sodium hydroxide in the range of 1 to 4 times mole of dihydrotagetone of formula (4) to the above said solution obtained in step (i);
k. maintaining the temperature between −15° C. to +90° C. during oxidation steps from (h) to (j) for a period ranging from 4-48 hours;
l. destroying the excess permanganate from the above reaction mixture with saturated solution of sodium bisulphite or sodium metabisulphite;
m. filtering the above reaction mixture, washing, acidifying, and removing the solvent under reduced pressure, followed by extraction and chromatography to obtain 2,6-dimethyl-4-oxo-heptanoic acid of formula (3) with 68% yield or more;
n. providing 4-oxo acid of formula (3) under stirring in a solvent selected from the group consisting of ether but not limited to tetrahydrofuran, dimethoxyetane and dioxane, alcohol but not limited to methanol, butanol and t-butyl alcohol, chlorinated solvent but not limited to dichloromethane and chloroform;
o. adding a base selected from the group consisting of but not limited to sodium bicarbonate or sodium hydroxide or potassium carbonate to the resultant solution to make salt of the oxy acid of formula (3);
p. reducing salt of oxo acid of formula (3) to hydroxy acid of formula (2) in the presence of a reducing agent selected from but not limited to sodium borohydride or lithium aluminium hydride in the range of 0.5-3 times mole at a reaction temperature varying from −15 to 50° C.;
q. removing the organic solvent under vacuum and acidifying the cooled aqueous alcoholic solution at −10° C. to 0° C. with an acid selected from the group but not limited to hydrochloric acid, sulphuric acid, acetic acid, acetic anhydride for a period ranging between 30 minutes to 8 hours and finally isolating the product 5-isobutyl-3-methyl-4,5-dihydro-2(3H)-furanone also known as 4-isobutyl-2-methyl-4-butanolide) of formula (1) in 76% or more yield by extraction and chromatography in usual manner.

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Heptanonic acid and furanone compounds and compositions

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Heptanonic acid and furanone compounds and compositions

Life of this patent

Abstract

Claims38