Biotransformation of organic sulfides .9. Formation of (S) para-substituted phenyl methyl sulfoxides by biotransformation using Helminthosporium species NRRL 4671

Phenyl methyl sulfides substituted in the para position with methyl, fluoro, chloro, bromo, cyano, nitro, amino, acyl, methoxy, thiomethyl and methylsulfinyl groups have been converted to (S) sulfoxides by biotransformation using Helminthosporium species NRRL 4671. The highest yields and enantiomeric excesses were obtained with bromo, cyano, methoxy, thiomethyl and methylsulfinyl substituents and in two cases (para-Br and -CN) the products could be crystallized to give (S) sulfoxide of greater than or equal to 96% ee.