Formal Cycloaddition of Disubstituted Ketenes with 2-Oxoaldehydes Catalyzed by Chiral N-Heterocyclic Carbenes
作者:Lin He、Hui Lv、Yan-Rong Zhang、Song Ye
DOI:10.1021/jo801494f
日期:2008.10.17
Chiral N-hetereocyclic carbenes were found to be efficient catalysts for the formal [2 + 2] cycloaddition reactions of alkyl(aryl)ketenes with 2-oxoaldehydes to afford beta-lactones with alpha-quaternary-beta-tertiary stereocenters in high yields with good diastereoselectivities and excellent enantioselectivities (up to 99% ee). Both alkyl(aryl)ketenes and diarylketene worked well in this reaction