Tri:methyl-di:hydro-pyran-4-one deriv. - useful as attractant for Stegobium paniceum

摘要

(A) (2S)-2,3-Dihydro-2,3,5- trimethyl-6-(1-methyl-2- oxobutyl) -4H-pyran-4-one of formula (I) is new. (B) intermediates for formulae (II) and (III) are also new. (I) is an attractant for the "bread beetle" Stegobium paniceum; it has higher pheromone activity than know isomer mixts. Preparation comprises fermenting 3-oxo-2-methyl butanic acid ester (V) (where R1 is 1-4C alkyl and R is a protecting gp.). with a yeast in the presence of a fermentable sugar at 0-50 deg.C to form (II) (3S)3-oxy-2-methyl butanic acid ester which by reaction with an R-supplying reagent (e.g. N-trimethylsilyl imidazole) at -50 to +50 deg.C to give (III) 4-methyl-heptan 3,5 dione. Then reacting (III) with a di(alkali metal) salt of 4-methylheptane-3,5-dione in the presence of a chelating agent at -80 to +50 deg.C, opt. followed by treatment with an acid or an acid salt gives (IV) (2S)-2-hydroxy 3,5,7-trimethyl decan 4,6,8 trione. (IV) is treated with a mineral acid or acidic ion exchanger at -20 to +50 deg.C.