Organic Letters 2013-09-20

Amino acid salts catalyzed asymmetric aldol reaction of tryptanthrin: a straightforward synthesis of phaitanthrin A and its derivatives.

Guowei Kang, Zhenli Luo, Chongxing Liu, Hang Gao, Quanquan Wu, Huayue Wu, Jun Jiang

Index: Org. Lett. 15(18) , 4738-41, (2013)

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Abstract

The first asymmetric synthesis of (S)-Phaitanthrin A and its derivatives via a catalytic aldol reaction of Tryptanthrin and ketones is described, in which the cheap, easily prepared natural amino acid salts exhibited unique catalytic ability; importantly, this methodology tolerates a range of substrates with different substitution patterns. Moreover, the synthetic utility of this strategy was further illustrated by a gram-scale synthesis of Phaitanthrin A.