1H-4,5,6,7-tetrahydro-1,3-diazepines. Part I: Synthesis, spectral and chemical properties of 1,2-diaryl derivatives

Article abstract of DOI:10.1002/jhet.5570370605

The synthesis of several 1,2-diaryl-1H-4,5,6,7-tetrahydro-1,3-diazepines 1 by cyclization of N-aryl-N′-benzoyltetramethylenediamines 2 is described. Two alternative synthetic routes to obtain precursors 2 are discussed, being that which employes pyrrolidine as starting material the most convenient. Nucleophilic attack of compounds 1 on methyl iodide affords 1,2-diaryl-1H-4,5,6,7-tetrahydro-1,3-diazepinium iodides 3. ¹H-nmr spectra of these compounds are unequivocally assigned by means of NOESY experiments. ¹H-nmr spectra of compounds 1 and 3 are analyzed and compared inter se and with those of compounds 1 run in the presence of trifluoroacetic acid-d. Reduction of compounds 1 with borane leads regiospecifically to N-aralkyl-N′-aryltetramethylenediamines 7.