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Start Over Author "Xue, Peng" Journal angewandte chemie international edition
14 results on '"Xue, Peng"'

5. Rhodium(III)‐Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3‐Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization

Author

Weiliang Yuan, Xue-Peng Zhang, Jiaqiong Sun, Peiyuan Wang, Rong Tian, and Xingwei Li

Subjects
chemistry.chemical_classification, Allylic rearrangement, Annulation, Enyne, 010405 organic chemistry, Enantioselective synthesis, Alkyne, General Medicine, General Chemistry, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Catalysis, Reductive elimination, Coupling reaction, 0104 chemical sciences, chemistry, Nucleophile
Abstract

Metal allyl species are versatile intermediates in a number of coupling reactions. However, Rh(III) π-allyls have been rarely elaborated in the context of asymmetric C-H functionalization. Reported herein is chiral Rh(III) cyclopentadienyl-catalyzed enantioselective synthesis of lactams and isochromenes via oxidative [4+1] and [5+1] annulation, respectively, between arenes and 1,3-enynes. The reaction proceeds via a C-H activation, alkenyl to allyl rearrangement, and nucleophilic cyclization cascade. The mechanistic details of the [4+1] annulation of N-methoxybenzamide and an 1,3-enyne have been elucidated by a combination of experimental and computational methods. DFT studies indicate that following the C-H activation and alkyne insertion, a Rh(III) alkenyl intermediate undergoes δ-hydrogen elimination of the allylic C-H via a six-membered ring transition state to produce a Rh(III) enallene hydride intermediate. Subsequent hydride insertion and allyl rearrangement affords several rhodium(III) allyl intermediates, and a rare Rh(III) η4 ene-allyl species with π-agostic interaction undergoes SN2'-type external attack by the nitrogen nucleophile, instead of C-N reductive elimination, as the stereodetermining step.

Published
2020

10. Role‐Specialized Division of Labor in CO2 Reduction with Doubly‐Functionalized Iron Porphyrin Atropisomers.

Author

Guo, Kai, Li, Xialiang, Lei, Haitao, Guo, Hongbo, Jin, Xiaotong, Zhang, Xue‐Peng, Zhang, Wei, Apfel, Ulf‐Peter, and Cao, Rui

Subjects
IRON porphyrins, DIVISION of labor, ATROPISOMERS, METALLOPORPHYRINS, CHEMICAL reactions, SCISSION (Chemistry)
Abstract

In enzymes, the active site residues function differently to promote chemical reactions. Such a role‐specialized division of labor has been rarely realized by synthetic catalysts. We report herein on catalytic CO2 reduction with Fe porphyrins decorated with two cationic N,N,N‐trimethylbenzylamine groups in cis‐ or trans‐arrangement. The cis‐isomer outperforms the trans‐isomer and reaches a TOFmax of 4.4×105 s−1 in acetonitrile using phenol proton source. Theoretical studies revealed that the two cationic units in the cis‐isomer are more effective than a single cationic unit to improve the CO2 binding, and more importantly, they function differently but cooperatively to promote the C−O bond cleavage: one interacts with the CO2‐adduct, while the other one interacts with the phenol molecule through electrostatic interactions. This work therefore presents a significant example of synthetic catalysts, which boost chemical reactions using a role‐specialized strategy for substrate activation. [ABSTRACT FROM AUTHOR]

Published
2022
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