Synthese von 2,2a,3,4-Tetrahydro-azeto[1,2-d]benz[b]-1,4-oxazin-2,4-dionen

Synthesis of 2,2a,3,4-Tetrahydroazeto1,2-d]benzob]-1,4-oxazine-2,4-diones The 1-(2-hydroxyaryl)-4-oxoazetidine-2-carboxylic acids 7c, 7d and 10 react with dicyclohexylcarbodiimide to give the title compounds 11, 12 and 13 . Compound 13 can also be obtained by nitration of 12 . The starting materials 7c , 7d and 10 are synthesized from the l-aryl-4-oxoazetidine-2,2-dicarboxylates 4a and 4b , which are available from 1 by a method analogous to that described by Sheehan²⁾ or via 8 and 9 .