Synthesis 2012; 44(22): 3432-3440
DOI: 10.1055/s-0032-1317499
feature article
© Georg Thieme Verlag Stuttgart · New York

Enantioselective Synthesis of (–)-Stemoamide

Xianwei Mi, a, b, Yan Wang, a, Lili Zhua, Renxiao Wangb, Ran Hong*a
  • aKey Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China   Email: rhong@sioc.ac.cn
  • bState Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, P. R. of China
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Publication History

Received: 13 August 2012

Accepted after revision: 02 October 2012

Publication Date:
25 October 2012 (eFirst)

Dedicated to Professor Guo-Qiang Lin on the occasion of his 70th birthday

Abstract

An enantioselective synthesis of (–)-stemoamide is presented. Noyori’s ruthenium complex catalyzed asymmetric transfer hydrogenation of an alkynone delivered the (S)-C8 stereogenic center in 97.7% ee. An iron(III) chloride promoted and bioinspired N-iminium ion cyclization afforded a 3:1 ratio of two diastereomers in favor of the cis-isomer. The diastereomeric ratio was enriched to 50:1 by a silver-catalyzed cycloisomerization. The subsequent dynamic ruthenium-catalyzed CO-insertion reaction secured an enantioselective total synthesis of (–)-stemoamide in 18% overall yield with high optical purity.

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