Calcium-Catalyzed Asymmetric Synthesis of 3-Tetrasubstituted Oxindoles: Efficient Construction of Adjacent Quaternary and Tertiary Chiral Centers

• DOI: 10.1021/acs.orglett.5b00749
• Publication Date: 2015-04-07T16:36:03Z
• Authors: Shota Shimizu; Tetsu Tsubogo; Pengyu Xu; Shu̅ Kobayashi
• Keywords: Quaternary carbon

Chiral Ca-catalyzed asymmetric addition reactions of 3-substituted oxindoles with N-Boc-imines afford 3-tetrasubstituted oxindole derivatives bearing adjacent quaternary and tertiary chiral centers, which are key structures for biological activities. Ubiquitous nontoxic Ca catalysts (1–10 mol %) work well in this reaction, high yields (up to 99%) selectivities >99% ee) the products wide substrate scope have been attained. The intermediary enolates also discussed.