The article describes a novel method for the regioselective dialkylation of unactivated alkenes using bimolecular homolytic substitution (S_H2) catalysis. This approach allows for the simultaneous formation of two C(sp^3)-C(sp^3) bonds, significantly accelerating the synthesis of drug-like molecules rich in C(sp^3) atoms. The reaction involves the in situ formation of three distinct radical species, which are then sorted by size and electronic properties to produce the desired dialkylated products. The method is applicable to a wide range of unactivated alkenes, including those with tertiary amines, alcohols, aryl halides, and other reactive functionalities. The authors demonstrate the scope of the reaction by successfully dialkyling complex bioactive molecules and incorporating various alkyl fragments through the use of primary alcohols and α-acyl chlorides as radical precursors. The proposed mechanism involves the formation of a long-lived triplet excited state, followed by reductive quenching and β-scission to produce the primary alkyl radical. This radical can be captured by a high-valent nickel S_H2 catalyst, leading to the formation of the desired dialkylated product. The study provides a general, modular strategy for the dialkylation of unactivated olefins and opens new avenues for the synthesis of C(sp^3)-rich small molecule libraries.The article describes a novel method for the regioselective dialkylation of unactivated alkenes using bimolecular homolytic substitution (S_H2) catalysis. This approach allows for the simultaneous formation of two C(sp^3)-C(sp^3) bonds, significantly accelerating the synthesis of drug-like molecules rich in C(sp^3) atoms. The reaction involves the in situ formation of three distinct radical species, which are then sorted by size and electronic properties to produce the desired dialkylated products. The method is applicable to a wide range of unactivated alkenes, including those with tertiary amines, alcohols, aryl halides, and other reactive functionalities. The authors demonstrate the scope of the reaction by successfully dialkyling complex bioactive molecules and incorporating various alkyl fragments through the use of primary alcohols and α-acyl chlorides as radical precursors. The proposed mechanism involves the formation of a long-lived triplet excited state, followed by reductive quenching and β-scission to produce the primary alkyl radical. This radical can be captured by a high-valent nickel S_H2 catalyst, leading to the formation of the desired dialkylated product. The study provides a general, modular strategy for the dialkylation of unactivated olefins and opens new avenues for the synthesis of C(sp^3)-rich small molecule libraries.