NMR studies of some rifamycins

The C-13 and H-1 NMR spectra of rifabutin 1 and five of its derivatives 2-6 , three of which are described for the first time, were assigned using 2D h omo- and heteronuclear correlation NMR spectroscopy, proton exchange with d euterium, and selective proton decoupling methods to one bond and long dist ance. The study was also extended to the other well-known ansamycin antibio tics, rifamycin S 7 and rifampicin 8. Previous interpretations for the know n compounds have been corrected. (C) 2001 Elsevier Science B.V. All rights reserved.