Functionalized α,β-ynones: efficient ligand for Cu catalyzed Sonogashira-type cross-coupling reaction

Abstract

Under the classic reaction conditions, a large excess of copper catalyst and N, O donor ligands were mandatory for the catalytic cross-coupling of Csp²–Csp bonds. Herein, we wish to report α,β-ynones as σ-, π-electron donating ligands for copper catalyzed Sonogashira-type reaction. As low as 0.25–2.5 mol% of L₁₁ (3-(4-bromophenyl)-1-(4-methoxyphenyl)prop-2-yn-1-one) significantly accelerated the 0.1–1.0 mol% of CuI catalyzed cross-coupling of aryl iodides with terminal alkynes and alkynylcarboxylic acids, respectively. This low-mol% catalyst system showed satisfactory activity and tolerance with 36 examples of substituted alkynes.