(o‐Phenylenediamino)borylstannanes: Efficient Reagents for Borylation of Various Alkyl Radical Precursors

(o‐Phenylenediamino)borylstannanes were newly synthesized to achieve radical boryl substitutions of a variety of alkyl radical precursors. Dehalogenative, deaminative, decharcogenative, and decarboxylative borylations proceeded in the presence of a radical initiator to give the corresponding organic boron compounds. Radical clock experiments and computational studies have provided insights into the mechanism of the homolytic substitution (SH2) of the borylstannanes with alkyl radical intermediates. DFT calculation disclosed that the phenylenediamino structure lowered the LUMO level including the vacant p‐orbital on the boron atom to enhance the reactivity to alkyl radicals in SH2. Moreover, C(sp3)‐H borylation of THF was accomplished using the triplet state of xanthone. Newly synthesized (o‐phenylenediamino)borylstannanes were utilized for radical borylations. Various alkyl radical precursors were applicable to dehalogenative‐, deaminative‐, dechalgenative‐, decarboxylative‐, and C−H borylation. The interaction of the p‐orbital on the boron atom with the SOMO of the alkyl radical was a key to this reaction.