Asymmetric Intramolecular CH Insertion of α-Diazoacetamides in Water by Dirhodium(II) Catalysts Derived from Natural Amino Acids
作者:Nuno R. Candeias、Carolina Carias、Luis F. R. Gomes、Vânia André、M. Teresa Duarte、Pedro M. P. Gois、Carlos A. M. Afonso
DOI:10.1002/adsc.201200101
日期:2012.11.12
The asymmetricdirhodium(II)-catalyzed intramolecular CH insertion of α-diazo acetamides in water is described for the first time. The use of natural α-amino acids as chiral ligands allowed the preparation of novel dirhodium(II) homochiral complexes by a simple procedure consisting of the in situ ligand exchange starting from dirhodium tetraacetate. The catalytic system was further reused up to 7 cycles
The axial coordination of N-heterocycliccarbene ligands onto dirhodium(II) complexes was examined, together with its role in the intramolecular C-H insertion reactions of α-diazoacetamides. The formation of a decarbonylated product occurs by a free-carbene mechanism in which the structures of the catalyst and the acetamide play a decisive role. carbenoids - carbenecomplexes - catalysis - diazo compounds
The rhodium(II)-catalyzed reaction of N-bis(trimethylsilylmethyl)diazoamides: steric, electronic and conformational effects
作者:Andrew G.H Wee、Sammy C Duncan
DOI:10.1016/s0040-4039(02)01273-x
日期:2002.8
insertion reaction occurs only at the other N-‘alkyl’ unit. In Cα-unbranched diazoamides, the inherent electroniceffects of the N-‘alkyl’ group influence the regioselectivity of the reaction. The N-BTMSM group also influences the conformational preference about the amide N–Cα bond in Cα-branched systems which, in turn, affects the regioselectivity of the reaction; substituent electroniceffects are subtle