Access to Chromenopyrrole via Tandem [3 + 2] Cycloaddition and Intramolecular C-O Coupling

J Org Chem. 2024 Jan 19;89(2):1331-1335. doi: 10.1021/acs.joc.3c02479. Epub 2024 Jan 3.

Abstract

A mild and concise method for the synthesis of chromenopyrrole from 2'-hydroxychalcone is devised. The reaction proceeds via an initial [3 + 2] cycloaddition on the C═C bond of 2'-hydroxychalcone and 1,3-dipolarophile, generated in situ by the reaction of ethyl isocyanoacetate and AgOAc. This is then followed by an intramolecular C-O bond formation with the -OH group and C5-H of the in situ generated pyrrole, leading to chromenopyrroles.