Oxiranyl Anions. Improved Synthesis of Trimethylsilyl-Substituted Oxiranyl Anions and Their Additions to Aldehydes and Ketones

Article abstract of DOI:10.1021/jo00278a013

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.