Cyclization-Carbonylation of 2-Alkynyl Primary Benzamides using p- Benzoquinone under Neutral Conditions

J Org Chem. 2024 Mar 15;89(6):3977-3986. doi: 10.1021/acs.joc.3c02812. Epub 2024 Feb 26.

Abstract

A palladium-catalyzed cyclization-carbonylation of 2-alkynyl primary benzamides 1 afforded methyl 3-substituted 1-methoxyisoquinoline-4-carboxylates 6 in good to moderate yields. In the case of mesylate 1r, 12 was obtained directly via a cyclization-carbonylation-cyclization cascade. Compounds 6 were converted to isoquinolin-1(2H)-ones 8 in good yields under microwave irradiation. In the case of the mesylate 6q, tricyclic isoquinolinone 10 was obtained in good yield. The reactions of thiophene-2-carboxamide derivatives also proceeded well.