Enantioselective Reactions of Configurationally Unstable α-Thiobenzyllithium Compounds

✍ Scribed by Shuichi Nakamura; Ryo Nakagawa; Yoshihiko Watanabe; Takeshi Toru

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 82 KB
• Volume: 112
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/(sici)1521-3757(20000117)112:2<361::aid-ange361>3.0.co;2-v

✦ Synopsis

Asymmetric induction that arises from organolithium substrates complexed to chiral ligands has emerged as an efficient and powerful method. Since Hoppe et al. showed a high enantioenrichment could be achieved in a lithiation reaction to provide a-oxygen-substituted dipole-stabilized carbanions, [1] the enantioselective reactions of dipole-stabilized a-heterocarbanions have been the subject of extensive studies. [2] These reactions generally afford products with high enantioselectivity through asymmetric deprotonation. However, a-thiocarbanions do not give products with such enantioselectivity, [3] possibly because these carbanions are configurationally unstable and rapidly racemize even at temperatures as low as À 78 8C. [4±6] Racemization of the aselenocarbanions also occurs, [4, 7] but Hoffmann et al. have [