ABSTRACT
In the present manuscript, we have developed a unique catalytic system by merging photoexcited ketone catalysis, halogen atom transfer (XAT), and nickel catalysis to forge C(sp3)-C(sp2) cross-electrophile coupling products from unactivated iodoalkanes and (hetero)aryl bromides. The synergistic catalytic system works under mild reaction conditions and tolerates a variety of functional groups; moreover, this strategy allows the late-stage modification of medicinally relevant molecules. Preliminary mechanistic studies reveal the role of the α-aminoalkyl radical, which further participates in the XAT process with alkyl iodides to generate the desired alkyl radical, which eventually intercepts with the nickel catalytic cycle to liberate the products in good to excellent yields.
ABSTRACT
Dual nickel-photoredox-enabled direct synthesis of amides through cross-coupling of cesium oxamates with aryl bromides has been developed. This methodology's key advantages are mild reaction conditions, utilizing organic dye as a photocatalyst, employing readily available starting chemicals as coupling partners, and late-stage carbamoylation of pharmaceutically relevant molecules. DFT studies suggested that the nickel catalytic cycle proceeds via a radical addition pathway prior to the oxidative insertion.
ABSTRACT
An efficient, catalyst- and additive-free, visible-light-driven radical C3-H alkylation of quinoxalin-2(1H)-one derivatives has been developed. This reaction utilizes alkyl-NHP-esters as an alkyl radical donor and quinoxalin-2(1H)-one derivatives as an alkyl radical acceptor. The operationally simple protocol works under mild reaction conditions and tolerates a variety of functional groups. Furthermore, the synthetic utility of the methodology was successfully implemented for synthesizing biologically relevant C3-alkyl substituted quinoxalin-2(1H)-one derivatives.
