Development of radical synthetic methodology using solid-phase organic synthesis

The synthesis of heterocycles using radical intermediates has become an important area of research in recent years. The aim of our research was to develop radical methodologies to construct heterocycles on solid-support. Tri-cyclic benzimidazole derivatives are desirable synthetic targets with a range of biological activity and are part of certain anti-tumour agents. Solid-supported radical reactions with substituted benzimidazoles were performed under different experimental conditions, including different solvents, three different resins (Wang, Merrifield and Rink) and different radical reagents. 4-Mercaptobenzoic acid moiety served as a traceless linker in radical ipso-substitution reactions of benzimidazole precursors attached to solid-support to construct tri-cyclic and tetracyclic benzimidazole adducts. The solution-phase radical ipso-substitution protocol was quite successfully translated onto solid-support. [Continues.]