A new route to diarylisoquinolones

Abstract

The lithium salts derived from position 3 of phthalides react with Schiff's bases to form a mixture of cis- and trans-2,3-disubstituted 4-hydroxy-3,4-dihydro-1(2H)-isoquinolones, the former isomer predominating. Acid-catalysed dehydration of the alcohols gives 2,4-disubstituted 1(2H)-isoquinolones, as a result of aryl group migration, whilst the cis-isomers, with methanesulphonyl chloride–pyridine as dehydrating agent, produce the 2,3-disubstituted 1(2H)-isoquinolones.