Selective C(sp³)-C(sp³) Cleavage/Alkynylation of Cycloalkylamides Enables Aminoalkyne Synthesis with Hypervalent Iodine Reagents

Abstract

Here, we report the selective C(sp3)-C(sp3) cleavage/alkynylation of cycloalkylamides for the aminoalkyne synthesis under mild photoredox catalysis conditions. γ- and δ-Aminoalkynes with versatile alkyne and amine substituents are efficiently constructed from cyclopropylamides and cyclobutylamides via amidyl radicals enabled by hypervalent iodine(III) reagents. The catalytic amount of cyclic iodine(III) BI’-OAc facilitated the single-electron oxidation and ring-opening alkynylation of cycloalkylamides, which were investigated by a series of mechanistic probing experiments. Various α-amino substitutions from the oxygen, sulfur, or carbon nucleophile trapping can be performed in gram scale, and the aminoalkyne products easily derivatize to indolizidines, presenting in versatile bioactive fused azacycles.