114693-78-6

Conditions for the metalation of trimethylsilyl-substituted oxiranes have been optimized.Utilizing sec-butyllithium in diethyl ether with tetramethylethylenediamine, oxiranyl anions possessing virtually all substitution patterns are generated in excellent yields.These unique carbanions are stable to α-elimination for periods of hours at -116 deg C.Most of the anions exhibit strict retention of configuration at the metalated carbon stereocenter, although one example displaying configurational inversion has been discovered.Reactions with aldehydes and ketones havebeen explored.Although low diastereoselectivity in reactions with alkyl aldehydes is observed, good to excellent diasterofacial additions to ketone and conjugated aldehydes can be achieved.

Pure cis-vinylsilanes are efficiently converted to cis-epoxysilanes which react smoothly with Li2Cu(CN)(CH2TMS)2 to provide the corresponding eryhro disilylated alcohol, in excellent yield and isomeric purity.Elimination of the elements of TMSOH affords e