Site-selective C–H functionalization of heteroarenes via photoinduced electron transfer

Abstract

The importance of site-selectively introducing functional groups to pyridine derivatives has been increased from the past study. The effective methods using pyridinium salt have been developed with high site-selectivity and multi-role activator. This dissertation described that exploiting photochemical activity of electron donor-acceptor complex or photoredox catalyst with N-amidopyridinium salt proceeds radical cross-coupling via photoinduced electron transfer strategy. Chapter 1 introduced divergent reaction pathways both visible-light-induced sulfonative pyridylaton of alkenes via electron donor-acceptor complex and C4-sulfonylation of N-heteroarenes with external base. Chapter 2 reported selective and mild method for the functionalization at the unactivated pyridylic C(sp3) –H bond via radical cascade. The reaction proceeds via in-situ generated alkylidene dihydropyridine intermediates by exploiting the reversible enolization of alkylpyridinium salts. These operationally simple and unique methods feature high chemoselectivity, a broad substrate scope, and excellent functional group tolerance.