

AN ALTERNATIVE APPROACH TO THE SYNTHESIS OF 5H-CHROMENO[4,3-b]PYRIDIN-5-ONE SYSTEM USING THE CLEAVAGE OF 5H,9H-PYRANO[2',3':5,6]CHROMENO[4,3-b]PYRIDINE-5,9-DIONES WITH BINUCLEOPHILES

Abstract
Hantzsch reaction has been successfully employed for a one-step assembling of pyranopyridine fragment to produce 5Н,9Н-pyrano[2',3':5,6]chromeno[4,3-b]pyridine-5,9-diones which upon treatment with binucleophiles undergo chemoselective γ-pyrone ring opening with the concomitant recyclization to give five-membered cycles, providing a concise route to 6-pyrazolyl(isoxazolyl)-5H-chromeno[4,3-b]pyridin-5-ones.
Keywords
carbonyl compounds; condensed chromones; isoxazoles,; pyrazoles; cyclization; recyclization
Latvian Institute of Organic Synthesis - Aizkraukles iela, 21, Riga, LV-1006, Latvia - hgs@osi.lv