Synthesis 2006(10): 1689-1696  
DOI: 10.1055/s-2006-926452
SPECIALTOPIC
© Georg Thieme Verlag Stuttgart · New York

Asymmetric Cyclopropanations and Cycloadditions of Dioxocarbenes

Paul Müller*, Yves F. Allenbach, Sabrina Chappellet, Ashraf Ghanem
Department of Organic Chemistry, University of Geneva, 30 quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Fax: +41(22)3793215; e-Mail: paul.muller@chiorg.unige.ch;
Further Information

Publication History

Received 16 February 2006
Publication Date:
27 April 2006 (online)

Abstract

Methods for enantioselective transfer of carbenes starting from precursors carrying two carbonyl groups have been elaborated. A one-pot procedure for olefin cyclopropanation with CH-acidic precursors via intermediate phenyliodonium ylides has been developed. The structure of the [Rh2{(S)-nttl}4] catalyst was optimized to produce up to 98% ee in olefin cyclopropanations with dimethyl malonate or Meldrum’s acid. Highly selective Rh(II)-catalyzed olefin cyclopropanations could be observed upon replacement of methyl diazoacetoacetate by methyl (silyloxy­-vinyl)diazoacetate. Enantioselective dipolar cycloadditions of diazo­pyruvate to polar olefins have been realized with Ru(II)-pybox catalysts.