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

Abstract

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%).

Graphical Abstract

Keywords:

• Pictet–Spengler
• 7-endo-trig cyclization
• benzodiazepine
• pyrimidinones
• benzodiazepines condensed pyrimidinones

Acknowledgments

I. K. Gujral Punjab Technical University, Kapurthala-144601, Punjab is acknowledged for providing research facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).