[2.2]Paracyclophane-based N-heterocyclic carbene as efficient catalyst or as ligand for copper catalyst for asymmetric α-silylation of N-tosylaldimines. Issue 12 (5th October 2016)

• Record Type: Journal Article
• Authors: Chen, Zhen; Huo, Yuwen; An, Ping; Wang, Xichao; Song, Chun; Ma, Yudao
• Is Part Of: Organic chemistry frontiers. Volume 3:Issue 12(2017:Dec.)
• Page Start: 1725
• Page End: 1737
• Publication Date: 2016-10-05
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/c6qo00386a
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : A carbene precursor plays a dual role as both an organocatalyst and as a ligand for the copper catalyst in asymmetric silylation. Abstract : A new series of chiral bicyclic 1, 2, 4-triazolium salts with various substituents in the pseudo- ortho position of the [2.2]paracyclophane skeleton has been successfully synthesized and applied to enantioselective α-silylations of N -tosylaldimines. The dual role of the new carbene precursor as an organocatalyst and as a ligand of the copper catalyst in the asymmetric silylation were investigated. The chiral carbene–copper catalyst has significant advantages over its carbene counterpart as an organocatalyst, affording the corresponding α-silyl amines in 77–99% yields over 20 examples and with 76–98% ee. In addition, the transannular electronic effects of the substituents in the pseudo- ortho position of the [2.2]paracyclophane skeleton were also discussed.