Coumaranone-2, 3-dicarboxylic acid was first reported3 in 1937 by two rather similar syntheses, both starting from isatin. The low yields (247?) of these workers were subsequently improved in this Laboratory4 to as high as 30.5%. While this latter paper was being written, a new synthesis of the acid, capable of extension to certain related compounds and homologs, was also rep~ rted.~ This Koelsch and Whitney synthesis was ...
