A NOVEL METHOD FOR CONVERTING DIHYDROTAGEONE INTO COCONUT FLAVOURED 5-ISOBUTYL -3- METHYL-4, 5-DIHYDRO-2(3H)- FURANONE WITH TWO CHIRAL CENTRES: AN ANALOGUE OF NATURAL WHISKY LACTONE AND OF COCONUT ALDEHYDE

摘要

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 (la) 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 (Ib) which is responsible for flavouring a wide range of food stuffs including baked goods and confectionery.