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Synfacts 2007(2): 0174-0174  
DOI: 10.1055/s-2006-955851
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

trans-Selective Synthesis of Substituted 1,2,4-Triazolidines

Contributor(s): Mark Lautens, Andrew Martins
M.-Z. Wang, H.-W. Xu, Y. Liu, M.-K. Wong, C.-M. Che*
The University of Hong Kong and Shanghai Institute of Organic Chemistry, P. R. of China
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Publication History

Publication Date:
23 January 2007 (online)

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Significance

In the presence of a Ru(II)-porphyrin catalyst, α-diazoesters decompose to a Ru carbenoid species, which upon reaction with an aromatic imine generates an azomethine ylide, which undergoes a 1,3-dipolar cycloaddition with alkylazo­dicarboxylates to stereoselectively afford 1,2,4-triazolidines in good to very good yields. Catalyst loadings are generally low (0.5 mol%), and the reaction is tolerant of several alkyl azodicarboxylates and both electron-rich and electron-poor aromatic imines; although an imine derived from an aliphatic amine afforded no product. Using a phenylmenthol-derived diazoester, the product was obtained with moderate diastereoselectivity.