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Asymmetric Synthesis of cis-Cyclopropane α-Amino Acids by Rhodium(II) Carboxylate
V. N. G. Lindsay, W. Lin, A. B. Charette*
Université de Montréal, Canada
21 January 2010 (online)
The authors reported the first catalytic enantioselective cyclopropanation of alkenes with α-nitro diazoacetophenones leading to the corresponding cyclopropanes in good to high yields and excellent diastereo- and enantioselectivities. All experimental results suggested that the halogenated rhodium carboxylate catalysts used in this process react through an all-up conformation, which is responsible for the high stereoselectivity. Also, this suggestion is consistent with DFT calculations made on non-halogenated analogues (A. DeAngelis, O. Dmitrenko, G. P. Yap, J. M. Fox J. Am. Chem. Soc. 2009, 131, 7230).