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Synfacts 2010(4): 0474-0474  
DOI: 10.1055/s-0029-1219509
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Iminium-Allenamine Cascade

Contributor(s): Benjamin List, Frank Lay
X. Zhang, S. Zhang, W. Wang*
University of New Mexico, Albuquerque, USA
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Publication History

Publication Date:
22 March 2010 (online)

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Significance

The authors report an oxa-Michael-Michael cascade using alkyl, aryl, and hetaryl alkynals 1 as Michael acceptors and various 2-(E)-(2-nitrovinyl)-phenols 2 as Michael donors/acceptors. The cascade is catalyzed by the chiral diphenyl prolinol TBDMS ether (3) and yields synthetically and biologically significant 4H-chromenes 5 in excellent yields (92-98%) and excellent enantiomeric ratios (from 99:1 up to >99.5:0.5).

Reviews: D. Enders, C. Grondal, M. R. M. Hüttl Angew. Chem. Int. Ed. 2007, 46, 1570-1581; A. Dondoni, A. Massi Angew. Chem. Int. Ed. 2008, 47, 4638-4660.