7-Endo-trig Pictet–Spengler type cyclization of 5-alkylidene/arylidene-amino-3H-pyrimidin-4-ones: An efficient and diastereoselective synthesis of pyrimido[4,5-b] [1,4]benzodiazepines.

The manuscript describes an efficient, atom economical synthesis of pyrimido[4,5-b][1,4]benzodiazepin-4-ones by relatively unexplored 7-endo-trig Pictet–Spengler type cyclisations. The synthetic methdodlogy involves the synthesis of different variants of 5-arylidene-amino-3H-pyrimidines and their p-toluene sulfonic acid mediated 7-endo-trig Pictet–Spengler type cyclisations to afford biologically relavent functionalized benzodiazepine condensed pyrimidinones such as pyrimido[4,5-b][1,4]benzodiazepines in good to excellent yields (82–94%). [ABSTRACT FROM AUTHOR]