Hydrogenolysis of the C?O bond of the 1,2,4-oxadiazine ring. Adams platinum hydrogenation of 3-aryl-5,6-dihydro-5-(substituted)-methylene-4H-1,2,4-oxadiazine derivatives

Adams platinum hydrogenation of Z-3-aryl-5,6-dihydro-5-(substituted)methylene-4H-1,2,4- oxadiazine ( 1a-f ) proceeds very slowly through C? O bond fission to give N-(1-substitutedcarbonyl-2-propylidene)benzamide ox-ime derivative 2 as the main product. In the reaction of 5-(arylcarbamoyl)methylene analogues 1d-f , 5-(aryl-carbamoyl)methyl-5,6-dihydro-3-phenyl-4H-1,2,4-oxadiazine ( 4 ) and N-aryl-3-hydroxybutanamide derivative 5 are also obtained as well as compound 2 .