Engaging Allene-Derived Zwitterions in an Unprecedented Mode of Asymmetric [3+2]-Annulation Reaction

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• 作者：Dr. Muthukumar G. Sankar ; Dr. Miguel Garcia-Castro ; Christopher Golz ; Prof. Dr. Carsten Strohmann and Dr. Kamal Kumar
• 刊名：Angewandte Chemie International Edition
• 出版年：2016
• 出版时间：August 8, 2016
• 年：2016
• 卷：55
• 期：33
• 页码：9709-9713
• 全文大小：1074K
• ISSN：1521-3773

文摘

Catalytic addition of chiral phosphine, that is, (R)- or (S)-SITCP, to an α-substituted allene ester generated a zwitterionic dipole. Under optimized reaction conditions, this dipole could engage isatine-derived N-Boc-ketimines in a novel mode of [3+2] annulation reaction. Pyrrolinyl spirooxindoles are thus afforded in high yields and with excellent enantioselectivities. The unprecedented annulation reaction successfully facilitated the construction of sp³-rich and highly substituted 3,2′-pyrrolidinyl spirooxindoles supporting many chiral centers.