Synthesis of heteroannulated 3-nitro- and 3-aminopyridines by cyclocondensation of electron-rich aminoheterocycles with 3-nitrochromone

3-Nitrochromone reacts with electron-rich aminoheterocycles (in glacial acetic acid at reflux) and anilines (in a mixture of DMF and TMSCl at 100–140 °C) to give a variety of hetero(carbo)annulated 3-nitropyridines. The reaction, involving a formal [3+3] cyclocondensation, proceeds in high yields and appears not to be influences greatly by the nature of the 1,3-C,N-dinucleophile as seen from the thorough scope study. The synthetic utility of the products was demonstrated by their conversion into the corresponding 3-aminopyridine derivatives. An NMR study and X-ray crystallographic analysis are reported.