An easy access to pyrimidine-fused azocine derivatives by thiophenol-mediated radical cyclization via 8- endo-trig mode

Abstract

An efficient route for the synthesis of eight-membered nitrogen heterocycles has been developed via a thiophenol-mediated intramolecular 8- endo-trig radical cyclization. The radical precursors were prepared using BF 3·Et 2O-catalyzed aza-Claisen rearrangement followed by the reaction with propargyl bromide. The alkenyl radicals are generated from thiophenol initiated by the benzoyl peroxide instead of commonly used AIBN for easy and facile isolation of the pure products.