An unmet challenge in radical relay difunctionalization of alkenes is the incorporation of two discrete transient radicals in a regiocontrolled manner under transition-metal-free conditions.Current protocols typically...An unmet challenge in radical relay difunctionalization of alkenes is the incorporation of two discrete transient radicals in a regiocontrolled manner under transition-metal-free conditions.Current protocols typically rely on persistent radicals or organometallic surrogates to trap radical adducts,thereby suppressing the undesired reactions but limiting the diversity.The direct use of two transient radicals remains synthetically elusive.We present a visible-light photoredox catalyzed alkene dialkylation strategy via a kinetically guided conjugative radical–radical coupling.This transition-metal-free approach enables two direct C(sp^(3))–C(sp^(3))bond formations across the C=C double bond using alkyl and allyl or benzyl radicals.Mechanistic investigations reveal the radical nature of the process.The success of this approach hinges on kinetically controlled radical addition to alkene substrates and the steric protection of the resulting radical adducts.This mild and functional-group-tolerant reaction exhibits broad substrate scope and tolerates structurally complex substrates,highlighting its potential for late-stage functionalization.展开更多
基金support of the National Natural Science Foundation of China(grant no.22271151)the Natural Science Foundation of Jiangsu Province(grant no.BK20211534)the US National Science Foundation(grant no.CHE-2154593)。
文摘An unmet challenge in radical relay difunctionalization of alkenes is the incorporation of two discrete transient radicals in a regiocontrolled manner under transition-metal-free conditions.Current protocols typically rely on persistent radicals or organometallic surrogates to trap radical adducts,thereby suppressing the undesired reactions but limiting the diversity.The direct use of two transient radicals remains synthetically elusive.We present a visible-light photoredox catalyzed alkene dialkylation strategy via a kinetically guided conjugative radical–radical coupling.This transition-metal-free approach enables two direct C(sp^(3))–C(sp^(3))bond formations across the C=C double bond using alkyl and allyl or benzyl radicals.Mechanistic investigations reveal the radical nature of the process.The success of this approach hinges on kinetically controlled radical addition to alkene substrates and the steric protection of the resulting radical adducts.This mild and functional-group-tolerant reaction exhibits broad substrate scope and tolerates structurally complex substrates,highlighting its potential for late-stage functionalization.
