Ethyl (4-N-acylaminopyridin-3-yl)glyoxylate and 5-azaisatin as new synthons for a route to various new polyheterocycles

From 4-N-protected-aminopyridines which were functionalized at their 3-position, 5-azaisatin and equivalent synthons where obtained. Via the use of the Pfitzinger reaction, these compounds provided an easy route to new and various polyheterocyclic compounds.