Pentavalent organoantimonial derivatives:: two simple and efficient synthetic methods for meglumine antimonate

Two simple and efficient procedures for the preparation of pentavalent antimony derivatives are described, using either antimony pentachloride (SbCl5) or potassium hexahydroxoantimonate (KSb(OH)(6)) as sources of antimony(V). These two new methods are evaluated for the synthesis of an important anti-leishmanial drug: meglumine antimonate. Using elemental (carbon, hydrogen, nitrogen) and thermal analysis, atomic absorption (antimony), proton NMR spectroscopy and high-resolution positive-ion electrospray ionization- mass spectrometry (ESI(+)-MS), products for the reaction with N-methyl-D-glucamine (NMG) using both the SbCl5 and KSb(OH)(6) methods were characterized and found to be similar to a commercial sample of the drug. The only notable difference was observed for the ESI-MS spectrum of the KSb(OH)(6) product, it displays the same pattern of ESI-generated ions as those of both the SbCl5 Product and the commercial drug, but with significantly different abundance ratios. NMR data indicate that the NMG molecules coordinate antimony in two different fashions, which suggests either the coexistence of two different complexes or the existence of a single major complex in which two NMG molecules are coordinated with antimony in an asymmetrical geometry. Copyright (C) 2003 John Wiley Sons, Ltd.