Selective Carbonyl-C(sp ) Bond Cleavage To Construct Ynamides, Ynoates, and Ynones by Photoredox Catalysis.

Carbon-carbon bond cleavage/functionalization is synthetically valuable, and selective carbonyl-C(sp ) bond cleavage/alkynylation presents a new perspective in constructing ynamides, ynoates, and ynones. Reported here is the first alkoxyl-radical-enabled carbonyl-C(sp ) bond cleavage/alkynylation reaction by photoredox catalysis. The use of novel cyclic iodine(III) reagents are essential for β-carbonyl alkoxyl radical generation from β-carbonyl alcohols, including alcohols with high redox potential (Epox >2.2 V vs. SCE in MeCN). β-Amide, β-ester, and β-ketone alcohols yield ynamides, ynoates, and ynones, respectively, for the first time, with excellent regio- and chemoselectivity under mild reaction conditions.