Palladium-catalysed heteroannulation with terminal alkynes: a highly regio- and stereoselective synthesis of (Z)-3-aryl(alkyl)idene isoindolin-1-ones

A highly regio- and stereoselective method for the synthesis of (Z)-3-aryl( alkyl)idene isoindolin-1-ones through palladium-copper catalysis is describ ed. 2-Iodobenzamide 1 and its substituted derivatives 2-10 were reacted wit h terminal alkynes 11-19 in the presence of (PPh3)(2)PdCl2, CuI, and Et3N i n DMF mostly at 80 degrees C for 16 h to yield the 2-alkynyl substituted be nzamides 20-38, 40-45, 77 which could then be cyclised with NaOEt in EtOH t o the 3-aryl(alkyl)idene isoindolin-1-ones 46-49, 51, 53-55, 57, 59-71, 73 and 75. In certain cases, the isoindolin-1-ones 50, 52, 56 and 58 could be directly obtained by the palladium-catalysed reactions. (C) 2000 Elsevier S cience Ltd. All rights reserved.