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.

DOI: 10.1021/jo801494f

---

Abstract

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.

see article for more examples

proposed mechanism

---

---

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.

---

Key Words

Lactones, Organocatalysis

---

ID: J42-Y2008-3080