Experimental Evidence for the All-Up Reactive Conformation of Chiral Rhodium(II) Carboxylate Catalysts: Enantioselective Synthesis of <i>cis</i>-Cyclopropane α-Amino Acids
作者:Vincent N. G. Lindsay、Wei Lin、André B. Charette
DOI:10.1021/ja9044955
日期:2009.11.18
of chiral Rh(II)-carboxylate catalysts are described in the first catalytic asymmetric cyclopropanation of alkenes with alpha-nitro diazoacetophenones. X-ray, solution NMR, and reactivity studies made on these complexes suggest that the level of asymmetric induction strongly depends on their active symmetry, which in turn relies on the nature of the chiral ligands' substituents. The catalyst's 'All
Asymmetric Rh(II)-Catalyzed Cyclopropanation of Alkenes with Diacceptor Diazo Compounds: <i>p</i>-Methoxyphenyl Ketone as a General Stereoselectivity Controlling Group
作者:Vincent N. G. Lindsay、Cyril Nicolas、André B. Charette
DOI:10.1021/ja201237j
日期:2011.6.15
α-PMP-ketone group were found to be effective carbene precursors for the highly stereoselective Rh(2)(S-TCPTTL)(4)-catalyzed cyclopropanation of alkenes (EWG = NO(2), CN, CO(2)Me). The resulting products were readily transformed into a variety of biologically relevant enantiopure molecules, such as cyclopropane α- and β-amino acid derivatives. Different mechanistic studies carried out led to a rationale for the