Synthesis of isoquinolones by visible-light-induced deaminative [4+2] annulation reactions

Abstract

Herein a metal-free approach for the synthesis of isoquinolone derivatives by means of photoinitiated deaminative [4+2] annulation of alkynes and N-amidepyridinium salts is described. This protocol exhibits a broad scope and good functional group tolerance and regioselectivity under benign reaction conditions. Preliminary studies suggest that the critical amide radical is derived from the photocatalytic cleavage of the N–N bond of the N-amidepyridinium salt, which adds to the triple bond of the alkyne and undergoes the annulation process to afford the desired isoquinolones.