ASYMMETRIC TRANSFORMATIONS BY DEPROTONATION USING CHIRAL LITHIUM AMIDES

摘要

Oer the past 25 years or so, chiral lithium amide bases have seen significant application in reactions that can be broadly described as asymmetric deproto-nations. Several reviews provide an overview of particular facets of the chiral lithium amide base repertoire. Developments in the methodology, including design and exploration of novel bases, moves toward catalysis, and applications to new types of substrates have increased the scope of the chemistry considerably. Chiral lithium amides are used successfully in several classes of asymmetric reactions, including (1) the rearrangement of symmetrical epoxides into allylic alcohols (Eq. 1), (2) the conversion of prochiral cyclic ketones into chiral enolates and the reactions thereof (Eq. 2), and (3) aromatic and benzylic functionalization tricarbonyl(η~6-arene)chromium(0) complexes. The desymmetrization of prochiral cyclic ketones has become a well-established strategy in organic synthesis, and has seen significant application in target-oriented synthesis. Typical chiral bases employed in asymmetric deprotonation processes are, for the most lithium amides 1-8.