Formal Cycloaddition of Disubstituted Ketenes with 2-Oxoaldehydes Catalyzed by Chiral N-Heterocyclic Carbenes
Lin He, Hui Lv, Yan-Rong Zhang and Song Ye*
*Beijing National Laboratory for Molecular Sciences, Laboratory of Chemical Biology, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China, Email: songyeiccas.ac.cn
L. He, H. Lv, Y.-R. Zhang, S. Ye, J. Org. Chem., 2008, 73, 8101-8103.
Chiral N-hetereocyclic carbenes are efficient catalysts for the formal [2 + 2] cycloaddition reactions of alkyl(aryl)ketenes with 2-oxoaldehydes to afford highly substituted β-lactones in high yields with good diastereoselectivities and excellent enantioselectivities. Both alkyl(aryl)ketenes and diarylketene worked well in this reaction.
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Chiral N-Heterocyclic Carbene Catalyzed Staudinger Reaction of Ketenes with Imines: Highly Enantioselective Synthesis of N-Boc β-Lactams
Y.-R. Zhang, L. He, X. Wu, P.-L. Shao, S. Ye, Org. Lett., 2008, 10, 277-280.