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
A new procedure for the highly diastereoselective synthesis of （1S）-trans-cyclopropane derivatives using a fructose derivative as the chiral auxiliary was developed. Chloroacetylated 1,2;4,5-di-O-isopropylidene-D-fr...A new procedure for the highly diastereoselective synthesis of （1S）-trans-cyclopropane derivatives using a fructose derivative as the chiral auxiliary was developed. Chloroacetylated 1,2;4,5-di-O-isopropylidene-D-fructopyranose was reacted with a tertiary amine to form the ammonium salt, which was treated with cesium carbonate to give the cyclopropane derivative through ylide intermediate. The described procedure provides an efficient method to synthesize optically pure dior poly-substituded cyclopropanes.展开更多
A highly efficient asymmetric cyclopropanation of trisubstituted olefins with methyl diazoacetate has been developed in terms of an elaborate modified chiral bisoxazoline/copper complex as a catalyst. A broad scope of...A highly efficient asymmetric cyclopropanation of trisubstituted olefins with methyl diazoacetate has been developed in terms of an elaborate modified chiral bisoxazoline/copper complex as a catalyst. A broad scope of substrates is compatible with this catalyst system, including various trisubstituted olefins bearing different aryl-, fused aryl-and alkyl-substituents, providing an easy access to optically active 1,1-dimethyl cyclopropanes in good yields with excellent diastereo-and enantio-selectivity.展开更多
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.
基金National Natural Science Foundation of China (Grant No. 20602001)
文摘A new procedure for the highly diastereoselective synthesis of （1S）-trans-cyclopropane derivatives using a fructose derivative as the chiral auxiliary was developed. Chloroacetylated 1,2;4,5-di-O-isopropylidene-D-fructopyranose was reacted with a tertiary amine to form the ammonium salt, which was treated with cesium carbonate to give the cyclopropane derivative through ylide intermediate. The described procedure provides an efficient method to synthesize optically pure dior poly-substituded cyclopropanes.
基金supported by the National Natural Science Foundation of China(21432011,21772224)Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDY-SSWSLH016)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000)the Youth Innovation Promotion Association CAS(2017301)the National Basic Research Program of China(2015CB856600)
文摘A highly efficient asymmetric cyclopropanation of trisubstituted olefins with methyl diazoacetate has been developed in terms of an elaborate modified chiral bisoxazoline/copper complex as a catalyst. A broad scope of substrates is compatible with this catalyst system, including various trisubstituted olefins bearing different aryl-, fused aryl-and alkyl-substituents, providing an easy access to optically active 1,1-dimethyl cyclopropanes in good yields with excellent diastereo-and enantio-selectivity.
