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1,178 results on '"Cheng, Jin‐Pei"'

208. Radical substituent effects of alpha-sulfonium groups

Author

Cheng, Jin-Pei, Liu, Bo, and Zhang, Xian-Man

Subjects
Sulfur compounds -- Research, Chirality -- Research, Biological sciences, Chemistry
Abstract

Alpha-sulfonium groups are radical stabilizing rather than radical destabilizing, as gleaned from theoretical calculations in an examination of the radical substituent effects of the alpha-sulfonium groups. Results showed that the radical-stabilizing effects of the alpha-dialkylsulfonium groups are smaller and with larger steric hindrance than those for the alpha-RS groups. They were also found to be associated with the free lone pair electrons of the sulfur atom in the sulfonium groups. The latter were found to be able to form a two-center three-electron bond with the unpaired electron of the radical.

Published
1998

209. Heterolytic and homolytic Y-NO bond energy scales of nitroso-containing compounds: chemical origin of NO release and NO capture

Author

Cheng, Jin-Pei, Xian, Ming, Wang, Kun, Zhu, Xiaoqing, Yin, Zheng, and Wang, Peng George

Subjects
Chemical bonds -- Research, Nitric oxide -- Research, Binding energy -- Research, Chemistry
Abstract

The first-ever Y-nitric oxide (NO) bond energy scale, where Y is the atom to which NO is attached, is established by direct calorimetric measurements and electrochemical data for three types of N-nitroso compounds. These bond scales establish a technique for determining the dissociation energy of Y-NO bonds in solution and pave the way for developing a complete data set of Y-NO bond energies for a wider range of organic and inorganic compounds.

Published
1998

223. Phosphoric Acid Catalyzed Asymmetric 1,6-Conjugate Addition of Thioacetic Acid to para-Quinone Methides.

Author

Dong, Nan, Zhang, Zhi-Pei, Xue, Xiao-Song, Li, Xin, and Cheng, Jin-Pei

Subjects
QUINONE, PHOSPHORIC acid, AROMATIC compounds, QUINONE methides, DIETHYLENETRIAMINEPENTAACETIC acid, PHOSPHOINOSITIDES
Abstract

An asymmetric 1,6-conjugate addition of thioacetic acid with para-quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur-containing compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water-bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O−H⋅⋅⋅π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis. [ABSTRACT FROM AUTHOR]

Published
2016
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