Acetyl Coenzyme-A抑制物質の研究 (第3報)

erythro-2-Methyl-3-phenylvaleric Acidの合成

抄録

The Reformatsky reaction of α-acetoxypropiophenone and ethyl 2-bromopropionate afforded 2-methyl-3-phenyl-4-methyl-Δ²-butenolide (I) as crystals. Catalytic reduction of (I) gave 2-methyl-3-phenyl-4-hydroxyvaleric acid γ-lactone (II), whose alkaline saponification resulted in partial isomerization to form a hydroxy acid (III), a mixture of stereoisomers. Warming of (III) in pyridine completed the isomerization and only one kind of γ-lactone (IX) was obtained, without contamination of an isomer. Saponifcation of (IX) afforded a hydroxy acid (III′) without being accompanied by isomerization. Methylation of (III′) with diazomethane to the methyl ester (IV′) and application of tosyl chloride to it in pyridine afforded the tosylate (V). Application of phenylmethanethiol to (V) to form the benzylthio compound (VI) and its desulfurization and saponification finally afforded erythro-2-methyl-3-phenylvaleric acid stereospecifically.