Abstract
The yellow substance found in rat bile after oral administration of 2-amino-3-ethoxycarbonyl-6-benzyl-4, 5, 6, 7-tetrahydrothieno[2, 3-c]pyridine (Y-3642) was confirmed to be identical with one of chemica1 degradation products (Ia) produced from Y-3642 under light-irradiation. Ia was reduced to Y-3642 with sodium borohydride. From the results of nuclear magnetic resonance and infrared absorption spectra, the structure of Ia was established as the carbonic acid salt of dihydropyridinium compound derived by dehydrogenation of Y-3642 at 7-position.
