STEREOSPECIFIC REDUCTIVE DESULFURIZATION OF VINYL SULFOXIDES WITH TERT-BUTYLLITHIUM AND AN INTERNAL PROTON SOURCE

Trienyl and allenyl phenyl sulfoxides can be reduced stereospecifically with retention of configuration in good yields using iert-butyllithium with methanol (MeOH) as an internal (in situ) proton source. The method can be easily modified to give stereospecifically deuterium-labeled compounds. While simple monoene sulfoxides afford attenuated yields of reduced olefin, the method is useful for the reduction of the more sensitive and complex polyene sulfoxides as exemplified by the reduction of trienyl sulfoxides 2b, 3b, and 9 and allenyl sulfoxide 10 and by a brief review of additional examples which have emerged from this laboratory. That the reaction proceeds through the direct protonation of sulfurane intermediates such as 35 or 35' is an attractive mechanistic hypothesis, but several other possibilities exist. A pathway involving a vinyllithium as a reactive intermediate is considered to be less likely. © 1990, American Chemical Society. All rights reserved.