Synthesis of pyrido[1,2-b][2,4]benzodiazepin-6(11H)-imines

Synthesis of Novel Pyrido[1,2-b][2,4]Benzodiazepine Derivatives

“…The assignment of the proton signals in 1 H NMR spectra and carbon signals in 13 C NMR spectra was completed on the base of COSY, NOESY, HMQC and HMBC experiments for compound 5a. The final confirmation of the structure of the pyrido[1,2-b] [2,4]benzodiazepine derivatives was based on X-ray data for 5a (Fig. 1).…”

“…of the salts 3a-e in AcOH leads to intramolecular reaction products; 6-aryl-11H-pyrido[1,2-b] [2,4]benzodiazepin-12-ium bromides (5a-e). The structures of the substances 5 were assigned based on mass spectrometry, IR and NMR spectral data.…”

“…Pyrido [1,2-b] [2,4]benzodiazepine derivatives are poorly studied compounds. At present, less than 40 representatives of the above system have been described, the majority of which are partially hydrogenated derivatives.…”

“…At present, less than 40 representatives of the above system have been described, the majority of which are partially hydrogenated derivatives. The first report of the synthesis of pyrido [1,2-b] [2,4]benzodiazepine derivatives appeared in 1971, 1 when the cyclisation of 2-amino-1-(2carboxybenzyl)pyridinium salts was described, which leads to 6-oxo-6,11-dihydro-derivatives of this heterocyclic system. A few methods for the synthesis of these compounds are known today.…”

“…2 In another example, the diazepine ring was added to a pyridine by using 2-bromomethylbenzoic acid derivatives. 1,[3][4][5] We now describe a new method for the synthesis of pyrido [1,2-b] [2,4]benzodiazepines which is based on the reaction of [2-(bromomethyl)phenyl](phenyl) methanone (о-bromomethylbenzophenone, 1) derivatives with 2-aminopyridines (2). Substances of type 1 are α-bromoacetophenone 7 viniloges, 6 which suggests the possibility of a cyclisation that is similar to the Chichibabin synthesis.…”