Acylmethylidenepyrrolo[1,2-c]oxazoles via [3+2]-cyclization of 2-acylethynylpyrroles with carbonyl compounds

Abstract

Acylethynylpyrroles, readily available from acylbromoacetylenes and pyrroles, smoothly undergo [3+2]-cyclization with ketones and aldehydes (room temperature) to give acylmethylidenepyrrolo[1,2-c]oxazoles. The reaction protocol meets the principles of the PASE (pot, atom, and step economy) paradigm to afford various pyrrolo[1,2-c]oxazoles, including spirocyclic ones, in up to 82% yield.