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Bis(phosphine) Monoxide Ligands for Asymmetric Conjugate Addition
A. Côté, V. N. G. Lindsay, A. B. Charette*
Université de Montréal, Canada
23 March 2007 (online)
This is an interesting contribution to the use of bis(phosphine) monoxides as hemilabile ligands for asymmetric catalysis. (R,R)-Me-DuPHOS monoxide (2) gave high enantioselectivity for the 1,4-addition of dialkyl zinc to nitroalkenes. Interestingly, 2 gave better selectivities than both the bisphosphine, Me-DuPHOS, and the Me-DuPHOS bisoxide. While most reports use diethyl zinc as nucleophile, dimethyl zinc also succeeds in giving the 1,4-adduct with good selectivity and yield.