Stereocontrolled synthesis of novel enantiomerically pure sulfides and selenides from (+)-camphor and (+)-camphor-10-sulfonyl chloride

Synthetic approaches to novel enantiomerically pure sulfides and selenides derived from (+)-camphor and (+)-camphor-10-sulfonate esters are described. Lewis acid mediated hemiacetal formation between a camphor-derived ketone and a thiol or selenol, and subsequent in situ reduction using triethylsilane selectively gives the exo-sulfide or -selenide in moderate overall yields. The initial sulfonate ester products can be converted into the corresponding sulfones by subsequent treatment with Grignard or organolithium reagents.