A kinetic study on the pairwise competition reaction of α-diazo esters with rhodium(II) catalysts:: Implication for the mechanism of Rh(II)-carbene transfer
The relative rate constants for the Rh(II)-mediated diazo decomposition of a series of para- or meta-substituted diazophenylacetates were measured through intermolecular competition. The kinetic data were further subjected to Hammett correlation analysis and were found to have better linear correlation with sigma (+). Reaction constants for four Rh(II) catalysts have been obtained, Rh-2(OAc)(4) (rho = -1.29 with sigma (+), r = -0.99), Rh-2(Ooct)(4) (rho = -1.31 with sigma (+), r = -0.99), Rh-2(acam)(4) (rho = -1.18 with sigma (+), r = -0.99), Rh-2(O2CCF3)(4) (rho = -1.46 with sigma (+), r = -0.99). The mechanistic implications of these data are discussed.
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页码:8139 / 8144
页数:6
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Taber D. F., 1991, COMPREHENSIVE ORGANI, V3, P1045