Ligand-Free and Recyclable Palladium(II) Acetate Catalyzes the Decarboxylative Cross-Coupling of Alkynyl Carboxylic Acids with Arylboronic Acids in Aqueous PEG-400

Abstract

A novel and ligand-free method was developed for the decarboxylative cross-coupling of alkynylcarboxylic acids with arylboronic acids. By using an environmentally friendly H2O–poly(ethylene glycol) (PEG-400) system as the reaction medium, a series of internal alkynes were synthesized in good yields and with remarkable selectivity. The Pd(OAc)2–H2O–PEG-400 catalytic system could be used for up to three cycles without any loss of activity, demonstrating the robustness of the approach.

Transition metal-catalyzed alkynylation reactions via alkynyl carbon–carbon bond cleavage

“…Tang and co-workers developed a ligand-free reaction for the decarboxylative cross-coupling of alkynyl carboxylic acids with arylboronic acids (Scheme 8). 21 In this Pd(OAc) 2 -catalyzed oxidative coupling reaction, a mixture of H 2 O–poly(ethylene glycol) (PEG-400) system was used as the reaction medium. The internal alkynes could be obtained in good yields.…”