Blue light-promoted [2 + 4] cycloaddition of phosphenes and N-acylimines: highly diastereoselective access to 3,4-dihydro-1,5,2-oxazaphosphinine 2-oxides

Abstract

A blue light-promoted reaction of phosphoryl diazomethanes and N-acylimines accesses 3,4-dihydro-1,5,2-oxazaphosphinine 2-oxides in satisfactory to excellent yields with excellent diastereoselectivities. The reaction is a tandem sequence of the light-induced Wolff rearrangement of phosphoryl diazomethanes to phosphenes and a subsequent concerted [2 + 4] heteroatom Diels–Alder cycloaddition of phosphenes and N-acylimines, affording highly diastereoselective trans-3,4-dihydro-1,5,2-oxazaphosphinine 2-oxides. The reaction features readily available starting materials, high atom-economy, no catalyst, high diastereoselectivity, and mild conditions.