Experimental and calculated 1H, 13C, 15N NMR spectra of famotidine

Famotidine, 3-[[[2-[(aminoiminomethyl)amino]-4-thiazolyl]methyl]thio]-N-(aminosulfonyl), is a histamine H-2-recepror blocker that has been used mainly for the treatment of peptic ulcers and the Zollinger-Ellison syndrome. Its NMR spectra in different solvents were reported earlier, however, detailed interpretation has not been done thus far. In this work, experimental H-1, C-13 and N-15 NMR spectra of famotidine dissolved in DMSO-d(6) are shown. The assignment of observed chemical shifts is based on quantum chemical calculation at the Hartree-Fock/6-31G* level. The geometry optimization of the famotidine molecule with two internal hydrogen bonds, i.e. [N(3)-H(23)...N(9) and N(3)...H(34)-N(20)], is done by using the B3LYP method with the 6-31G* basis set. (C) 2001 Elsevier Science B.V. All rights reserved.