Synthesis of N-Arylisoindolin-1-ones via Pd-Catalyzed Intramolecular Decarbonylative Coupling of N-(2-Bromobenzyl)oxanilic Acid Phenyl Esters

Ethyl and phenyl oxanilates were readily prepared from N-(2-bromobenzyl)anilines and oxalyl chloride monoethyl and monophenyl esters, respectively. It was found that the ethyl oxanilate survived in the presence of K2CO3 in DMA at 120 degrees C and underwent an intramolecular direct arylation using Pd(OAc)(2)-dppf, furnishing the 5,6-dihydrophenanthridine derivative. In contrast, the corresponding phenyl oxanilates decomposed upon exposure to K2CO3 in DMA at 120 degrees C and were transformed into N-arylisoindolin-1-ones via Pd(OAc)(2)-dppf-catalyzed intramolecular decarbonylative coupling. Except for the 4-methoxy-substituted oxanilic acid phenyl ester, other phenyl oxanilates possessing electron-withdrawing (NO2, Cl) and weak electron-donating (Me) substituents provided the N-arylisoindolin-1-ones in 43-80% yields.