Microbial Oxidation of Alkyl Aryl Sulfides to the Corresponding Optically Active Sulfoxides

Abstract

Incubation of alkyl aryl sulfides with growing cells of Corynebacterium equi IFO 3730 afforded the corresponding sulfoxides and sulfones. The selectivity for the formation of sulfoxides over sulfones was higher with sulfides which have shorter alkyl chains. When methyl sulfides were used as substrates, formation of the corresponding sulfones was completely suppressed. Sulfoxides were revealed to have 87 ~ 100% optical purities as to the (R) absolute configuration by HPLC analysis. The culture conditions seriously influenced the yield of oxidation products. High conversion of sulfides was attained when the reaction was carried out with growing cells in the logarithmic phase, in medium containing hexadecane as the carbon and energy source.