Indole Alkaloids Synthesis via a Selective Cyclization of Aminocyclopropanes

Authors

  • Filippo De Simone SCS-DSM Award for best poster presentation, Ecole Polytechnique Fédérale de Lausanne Laboratory of Catalysis and Organic Synthesis EPFL SB ISIC LCSO BCH 4306 CH-1015 Lausanne, Switzerland
  • Jérôme Waser Ecole Polytechnique Fédérale de Lausanne Laboratory of Catalysis and Organic Synthesis EPFL SB ISIC LCSO BCH 4306 CH-1015 Lausanne, Switzerland. jerome.waser@epfl.ch

DOI:

https://doi.org/10.2533/chimia.2012.233

Keywords:

Activated cyclopropanes, Alkaloids, Heterocycles, Regioselectivity, Total synthesis

Abstract

The continuous progress in medicinal chemistry requires more versatile synthetic strategies for the generation of large libraries of active compounds and their analogues. As a result, the research for new effective cyclization and cycloaddition reactions is an essential task in organic chemistry. In 2008 we developed the first catalytic formal homo-Nazarov reaction starting from activated cyclopropanes. Herein we report the extension of the catalytic formal homo-Nazarov cyclization to aminocyclopropanes. Highly diastereoselective cyclizations were obtained via an acyliminium intermediate generated through opening of the cyclopropane. An excellent control over the regioselectivity of either the C–C or C–N cyclization in the case of free indoles as nucleophilic partners was achieved. The utility of the developed methodology was demonstrated by the generation of the polycyclic scaffolds of Aspidosperma and Gonioma natural products starting from a common intermediate. Based on this method, a formal total synthesis of the alkaloid aspidospermidine and the total synthesis of the alkaloid goniomitine are presented. Finally, the scope and limitations of our methodology are discussed on an extended range of vinyl-cyclopropyl ketones with cyclic or acyclic carbamates, as well as ethers as donor groups on the cyclopropane.

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Published

2012-04-25