Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiom...Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiomeric excess of up to 91.8%. A mechanism that predicts the observed results accurately was proposed.展开更多
A new C 2 symmetric chiral Schiff base compound A with relatively flexible chiral environment was synthesized from L (+) tartaric acid. Its structure was determined by NMR, IR, MS etc, and its preponderant conformatio...A new C 2 symmetric chiral Schiff base compound A with relatively flexible chiral environment was synthesized from L (+) tartaric acid. Its structure was determined by NMR, IR, MS etc, and its preponderant conformation was modeled by CS Chem 3D Program. The results showed that its structure is not in a plane and has a big chiral cavity. It was showed that the complex B has different catalytic performance in asymmetric cyclopropanation of styrene and DMHD (2,5 dimethyl 2,4 hexadiene) with diazoacetate. The catalytic mechanism was also discussed.展开更多
文摘Four stereoisomers of a copper-(Schiff-base) complex with double chiral centers were applied to catalyze the asymmetric cyclopropanation. Two of the stereoisomers were also efficient catalysts affording high enantiomeric excess of up to 91.8%. A mechanism that predicts the observed results accurately was proposed.
文摘A new C 2 symmetric chiral Schiff base compound A with relatively flexible chiral environment was synthesized from L (+) tartaric acid. Its structure was determined by NMR, IR, MS etc, and its preponderant conformation was modeled by CS Chem 3D Program. The results showed that its structure is not in a plane and has a big chiral cavity. It was showed that the complex B has different catalytic performance in asymmetric cyclopropanation of styrene and DMHD (2,5 dimethyl 2,4 hexadiene) with diazoacetate. The catalytic mechanism was also discussed.
