Diastereoselective Generation of C₂-Azlactonized 2H-Chromenes via Brønsted acid-Catalyzed Oxo-Cyclization of Propargyl Alcohols

Meng-Ying Hao, Min-Hua Huang, Xin-Yu Gu, Tian-Shu Zhang, Xiao-Tong Zhu,* Wen-Juan Hao,* Bo Jiang*

A new Brønsted acid-catalyzed oxo-cyclization of propargyl alcohols with azlactones to synthesize C₂-azlactonized 2H-chromenes has been established that uses 1,1’-binaphthyl-2,2’-diyl hydrogen phosphate (BiNPO₄H) as the catalyst and gives excellent diastereoselectivities (≥19:1 dr) in most cases. This protocol tolerates high compatibility with various substituents of substrates, offering a catalytic and useful entry to fabrication of synthetically important C₂-functionalized 2H-chromene scaffold.

J. Org. Chem. 2022, 87, 1518-1525; DOI: 10.1021/acs.joc.1c02299