Thermally Induced [3 + 2] Cycloaddition of Alkynyl-Tethered Diazoamides: Synthetic and Mechanistic Insights

Cheng Zhang, Jingjing Huang, Lihua Qiu^*（邱丽华）, and Xinfang Xu^*（徐新芳）

College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China

Org. Lett., 2016, 18 (23), pp 6208–6211

A general and unprecedented thermally induced formal [3 + 2] cycloaddition has been developed that provides a general access to fused lactam derivatives in high to excellent yields with broad substrate scope. In comparison with the reported metal-catalyzed carbene/alkynyl metathesis, this is the only example in this area under catalyst-free conditions with excellent selectivity. Mechanistic studies indicate that the 3H-pyrazole is the key intermediate in this cascade reaction, which is confirmed spectroscopically for the first time.

链接：http://pubs.acs.org/doi/abs/10.1021/acs.orglett.6b03288