Asymmetric approach to the pentacyclic skeleton of Aspidosperma alkaloids via enantioselective intramolecular 1,3-dipolar cycloaddition of carbonyl ylides catalyzed by chiral dirhodium(II) carboxylates

TETRAHEDRON LETTERS

卷:50

Article

Nambu, Hisanori¹  Hikime, Mayuka¹  Krishnamurthi, Janagiraman¹  Kamiya, Megumi¹  Shimada, Naoyuki¹  Hashimoto, Shunichi¹ 

[1] Hokkaido Univ, Fac Pharmaceut Sci, Sapporo, Hokkaido 0600812, Japan

关键词: Carbonyl ylides;    1,3-Dipolar cycloadditions;    Chiral dirhodium(II) carboxylates;    Vindorosine;   

DOI  :  10.1016/j.tetlet.2009.03.142

来源: Elsevier

【 摘 要 】

This Letter describes asymmetric tandem carbonyl ylide formation-intramolecular 1,3-dipolar cycloaddition reaction of diazo imides containing a tethered indole catalyzed by chiral dirhodium(II) carboxylates as ail approach to the pentacyclic skeleton of Aspidosperma alkaloids. The cycloaddition of carbonyl ylides derived from indolyl-substituted 2-diazo-5-imido-3-ketoesters Under the influence of dirhodium(II) tetrakis[N-tetrachlorophthaloyl-(S)-tert-]leucinate], Rh-2(S-TCPTTL)(4), provides cycloadducts in moderate yields and enantioselectivities of up to 66% ee as well as with perfect endo diastereoselectivity. This is the first example of asymmetric induction in an intramolecular cycloaddition of a carbonyl ylide across an indolyl pi-bond. (C) 2009 Elsevier Ltd. All rights reserved.

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