Synthesis of aryl alkynyl carboxylic acids and aryl allrynes from propiolic acid and aryl halides by site selective coupling and decarboxylation

The coupling of propiolic acid with aryl iodides afforded the aryl allcynyl carboxylic acids and aryl allcynes in generally good yields. Aryl alkynyl carboxylic acids were obtained when the reaction was performed in the presence of Pd(PPh3)(2)Cl-2 (2.5 mol %), dppb (5.0 mol %) and DBU (5 equiv) at 50 C. For the synthesis of the terminal aryl alkynes, the reaction was conducted in the presence of Pd(PPh3)(2)C-12 (2.5 mol %), dppb (5.0 mol %), DBU (5.0 equiv), and Cu(acac)2 (10 mol %) at 25 C for 5 h, and further reacted at 60 C for 6 h. (C) 2011 Elsevier Ltd. All rights reserved.