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The amino group represents one of the most prevalent structural motifs in organic chemistry. Therefore, application of amines as alkylating agents in synthesis is highly compelling. Herein, we present a metal-free photoredox strategy for the formation of C(sp3)–C(sp) and C(sp3)–C(sp2) bonds from redox-activated primary amine derivatives. The developed reaction of 2,4,6-triphenylpyridinium salts with alkynyl p-tolylsulfones, leading to functionalized alkynes, is easily scalable and offers broad substrate scope, high chemoselectivity, and mild conditions. Its potential is also highlighted by diversification of complex molecular scaffolds. Additionally, the approach is also suitable for synthesis of (E)-alkenes from vinyl phenyl sulfones. Mechanistic studies contribute to the elucidation of unexpected differences in reactivity of primary and secondary alkyl substituted pyridinium salts.
Ociepa et al. (Fri,) studied this question.