Regiodivergent Conversion of Alkenes to Branched or Linear Alkylpyridines.

Herein we report a practical protocol for the visible-light-induced regiodivergent radical hydropyridylation of unactivated alkenes using pyridinium salts. This approach provides a unified synthetic platform to control the regioselectivity of the synthesis of linear or branched C4-alkylated pyridines. A remarkable selectivity switch from the anti-Markovnikov to the Markovnikov product can be achieved by the addition of tetrabutylammonium bromide. The versatility of this protocol is further demonstrated based on the late-stage functionalization in pharmaceuticals.