Experimental evidence for the all-up reactive conformation of chiral rhodium(II) carboxylate catalysts: enantioselective synthesis of cis-cyclopropane alpha-amino acids.
Useful empirical insights onto the enantioinduction process 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 Up' reactive conformation resulted in being necessary to obtain good stereoselectivity, and the resulting products are shown to be key intermediates in a concise synthesis of highly enantioenriched cis-cyclopropane alpha-amino acids.
Lindsay
Vincent N G
VN
Department of Chemistry, Université de Montréal, P.O. Box 6128, Station Downtown, Québec, Canada H3C 3J7.
Lin
Wei
W
Charette
André B
AB
D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
D000596:Amino Acids; D002264:Carboxylic Acids; D003521:Cyclopropanes; D009942:Organometallic Compounds; D012238:Rhodium