Synlett 2002(6): 0851-0862
DOI: 10.1055/s-2002-31891
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© Georg Thieme Verlag Stuttgart · New York

Linked Pummerer-Mannich Ion Cyclizations for Heterocyclic Chemistry

Albert Padwa*, Scott K. Bur, Diana M. Danca, John D. Ginn, Stephen M. Lynch
Department of Chemistry, Emory University, Atlanta, GA 30322, USA
e-Mail: chemap@emory.edu;
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Publikationsverlauf

Received 24 July 2001
Publikationsdatum:
07. Februar 2007 (online)

Abstract

Sequential transformations enable the facile synthesis of complex target molecules from simple building blocks in a single preparative step. As part of a program concerned with new methods for alkaloid synthesis, we have been utilizing a linked Pummerer/N-acyliminium ion cyclization sequence because this combination offers unique opportunities for the assemblage of complex target molecules. Cyclic 2-methylthio-5-amidofurans possessing tethered π-bonds were prepared from various amido dithioacetals. Upon heating, these systems undergo an intramolecular 4+2-cycloaddition reaction. The initially formed Diels-Alder cycloadduct further rearranges by ring opening of the oxygen bridge followed by a subsequent 1,2-methylthio shift. The method has been successfully applied to several different families of alkaloids.

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Padwa, A.; Danca, M. D. Org. Lett. 2002, 4, in press.