Synthetic Potential of Configurationally Unstable Chiral Carbanions

This account presents our recent efforts in exploring the synthetic potential of configurationally labile chiral carbanions next to electron-withdrawing groups that have been considered to be impossible even to generate. We used epoxysilane rearrangement to generate a chiral carbanion whose chirality was transformed from epoxide. The detailed analysis of the process showed that a carbamoyloxy group plays a more prominent role in fixing a chiral lithiocarbanion than expected. This understanding has led to the successful development of a method that allows enantioselective trapping of an α-chiral carbanion of acyclic nitrile by a carbon electrophile. During the course of these studies, we have found that the configurational stability of a carbanion highly depends on the solvent and we have proposed that the dependency is attributable to the ratio of CIP and SIP associated with their solvated structures.