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DOI: 10.1055/s-2006-926452
Asymmetric Cyclopropanations and Cycloadditions of Dioxocarbenes
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.
Key words
carbenoids - catalysis - diazo decomposition - phenyliodonium ylides - rhodium