Photochemical double 5-exo cyclization of alkenyl-substituted dithienylacetylenes: efficient synthesis of diarylated dithienofulvalenes

Abstract

Smooth and selective: Upon photoirradiation, bis(3-alkenyl-2-thienyl)acetylenes smoothly and selectively undergo double 5-exo-dig cyclization to produce a series of thiophene-fused pentafulvalenes with various aryl substituents. In this fused π-conjugated skeleton, the fused thiophene rings and the aryl substituents significantly modulate the electronic structure of the pentafulvalene skeleton.

Keywords: cyclization; pentafulvalene; photoreaction; redox properties; π conjugation.