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DOI: 10.1055/s-2007-968621
Copper-Catalyzed Enantioselective N-H Insertion Reactions
B. Liu, S.-F. Zhu, W. Zhang, C. Chen, Q.-L. Zhou*
Nakai University, Tianjin, P. R. of China
Publication History
Publication Date:
22 June 2007 (online)
Significance
A highly enantioselective catalytic insertion of α-diazoesters into N-H bonds is reported. The catalyst is prepared from a Cu(I) source, a spiro-bisoxazoline ligand, and a BARF counterion. A wide range of substituted anilines and naphthalenamines could be used for the insertion reaction with complete conversions observed within two hours and high yields and enantioselectivities were obtained. However, an electron-donating group in the para position of a phenyl-substituted aniline or a halogen at the ortho position resulted in slightly lower enantioselectivities for unknown reasons. The ester group on the diazoester could be changed with negligible effect; however, the diazo substituent is more sensitive and can lead to lower yields or ee values. No enantioselectivity was induced with N-methylaniline and benzamide, and cyclohexylamine was inert under the reported conditions.