Stereochemical studies on the polyene macrolide nystatin A1: the hydroxyl groups in the C-1—C-10 fragment are all-syn
Résumé
Two monoacetylated fragments 1 and 2 corresponding to the C-1—C-10 portion of nystatin A1 have been prepared by controlled degradation. The 3R, 5R and 7R relative configurations at the asymmetric centers of these fragments were determined by 2D-proton phase-sensitive DQF-COSY nmr and nOe difference spectroscopy.The 3R*, 5R* and 7R* relative configurations at the asymmetric centers of C-1–C-10 fragments of nystatin A. were determined by 2D-proton phase-sensitive bQF-COSY nmr and nOe difference spectroscopy.