Synthesis of 6-substituted 6-nitroperhydro-1,4-diazepines via novel tandem retro-Henry and Mannich/Michael reactions

N,N'-Dibenzyl-6-hydroxymethyl-6-nitroperhydro-1,4-diazepine was converted into a nitronate via retro-Henry reaction, followed by either Michael reaction with several acrylic derivatives or Mannich reaction with different amines, thus leading to 6-substituted 6-nitroperhydro-1,4-diazepines. The tandem retro-Henry/Mannich reaction was also carried out using benzylamine as base, solvent, and reagent at the same time. Selective hydrogenation of the nitro group and complete hydrogenolysis were also successfully achieved.