New efficient synthesis of polysubstituted benzo[d]pyrido[1′,2':1,2]imidazo[4,5-f][1,3]diazepines and pyrido[2′,1':2,3]imidazo[1,5-c]quinazolin-7-ium salts via Groebke-Blackburn-Bienaymé/Staudinger/aza-Wittig/carbodiimide-mediated annulation sequence

A new efficient synthesis of polysubstituted benzo[d]pyrido[1′,2':1,2]imidazo[4,5-f][1,3]diazepines and pyrido[2′,1':2,3]imidazo[1,5-c]quinazolin-7-ium salts via sequential Groebke-Blackburn-Bienaymé/Staudinger/aza-Wittig/carbodiimide-mediated annulation has been developed. The three-component Groebke-Blackburn-Bienaymé reactions of 2-azidobenzaldehydes 1 , isocyanides 2 , and 2-aminopyridines 3 produced the azide intermediates 4 , which were treated sequentially with triphenylphosphine and isocyanates to give polysubstituted benzo[d]pyrido[1′,2':1,2]imidazo[4,5-f][1,3]diazepines and pyrido[2′,1':2,3]imidazo[1,5-c]quinazolin-7-ium chlorides in good yields. [Display omitted] [ABSTRACT FROM AUTHOR]