Biosynthesis of Certain Gamma-Substituted-Gamma-Butyrolactones Present in Film Sherries

Abstract

Ethyl 4-oxobutyrate-2-¹⁴C added to a simulated sherry under an actively growing film of S. fermentati yielded radioactive gamma-butyrolactone, diethyl succinate, ethyl 4-oxobutyrate diethyl acetal, an unidentified ester, and 4-hydroxy-5-ketohexanoic acid gamma-lactone, thus confirming the pathways proposed earlier for their formation. When unlabeled ethyl 4-oxobutyrate was used in similar experiments, the same compounds and 4,5-dihydroxyhexanoic acid gamma-lactone had their concentrations enhanced. 4-Hydroxy-5-ketohexanoic acid gamma-lactone isolated from the latter experiment was optically active (+) and showed a specific rotation vs. wavelength "plain curve."