Synthesis of 4-styrylcoumarins via FeCl3-promoted cascade reactions of propargylamines with β-keto esters

Org Biomol Chem. 2019 Apr 17;17(16):4005-4013. doi: 10.1039/c9ob00323a.

Abstract

A versatile and highly regioselective FeCl3-promoted tandem cyclization reaction of in situ generated alkynyl o-quinone methides (o-AQMs) with β-keto esters has been developed on the basis of the mode involving an intermolecular 1,4-conjugate addition/alkyne-allene isomerization/intramolecular transesterification/isomerization cascade. Using this method, a variety of diversely substituted 4-styryl-2H-chromen-2-ones were prepared with good efficiency and exclusive site-selectivity.