Research Projects

The selective functionalization of olefins via radical pathways has emerged as a powerful tool in modern synthetic chemistry, enabling the direct construction of C–C and C–N bonds under mild conditions. In this project, we explore a dual catalytic strategy combining cobalt catalysis with visible-light photoredox activation to achieve hydroalkylation and hydroamination of olefins. The transformation proceeds via a radical-polar crossover (RPC) mechanism, allowing for divergent reactivity under reductive or oxidative conditions. Central to this methodology is the synergistic interplay between the cobalt-mediated hydrogen atom transfer (MHAT) process and the photoredox catalyst, which generates or quenches alkyl radicals at controlled redox states. The reductive RPC conditions enable Markovnikov-selective hydroalkylation, while oxidative RPC channels facilitate the formation of C–N bonds through amination. These strategies enable highly regioselective synthesis of alkylated/aminated scaffolds from simple olefins and radicals. In this proposal, we design two sustainable and economically viable synthetic strategies for photocobalt-catalyzed hydroalkylation and hydroamination reactions, aiming to expand the scope and utility of these transformations in complex molecule synthesis: 1. Markovnikov photocatalytic hydroalkylation of alkenes by merging with cobalt catalysis (Reductive Radical Polar cross over). 2. Markovnikov photocatalytic hydroamination of alkenes by merging with cobalt catalysis (Oxidative Radical Polar cross over). In strategy 1, we plan for a redox-neutral synthesis of saturated hydrocarbons from benzenesulfonohydrazide. Initially, the low-valent Co(I) species, upon protonation, generate reactive Co(III)–H, which would engage in HAT to the less substituted position of the alkene, yielding a carbon-centered radical. This intermediate, in equilibrium with a Co(III)–alkyl complex, could then undergo photoinduced single-electron reduction to either form a carbanion or regenerate Co(I). The resulting nucleophilic species would subsequently react with benzenesulfonohydrazide, forging a new C–C bond and delivering branched hydrocarbons. In strategy 2, we plan to synthesize various alkyl amines by harnessing triple cobalt/photo-redox/ proton donor catalysis. In this strategy also the low-valent Co(I) species, upon protonation, generate reactive Co(III)–H intermediates capable of delivering a hydrogen atom to the alkene substrate, generating a carbon-centered radical along with a Co(II) species. This intermediate can undergo radical recombination to form a Co(III)–alkyl complex, which is then oxidized via photoredox catalysis to a high-valent Co(IV)–alkyl species. The resulting electrophilic intermediate serves as a carbocation equivalent, enabling nucleophilic attack by dioxazolones to forge the C–N bond with Markovnikov selectivity. For these two approaches, selective photoredox catalysts, the cobalt complexes, and proton donors are essential.