Structural and 1H and 13C NMR analysis of two new glabretal triterpenoid derivatives from Guarea jamaicensis

The H-1 and C-13 NMR spectra of the glabretal derivatives, 21,24-epoxy-3 alpha ,7 alpha ,21,23-tetraacetoxy-25-hydroxy-4 alpha ,4 beta ,8 beta -trimethyl-14,18-cyclo-5 alpha ,13 alpha ,14 alpha ,17 alpha -cholestane and 21,23-epoxy-3 alpha ,7 alpha ,21,24,25-pentaacetoxy-4 alpha ,4 beta ,8 beta -trimethyl-14,18-cyclo-5 alpha ,13 alpha ,14 alpha ,17 alpha -cholestane, obtained from an acetylated fraction of extracts of Guarea jamaicensis, were completely assigned. ID NMR and a number of 2D shift correlated NMR experiments, (HH)-H-1-H-1-COSY, H-1,C-13-HSQC-(1)J(CH), H-1,C-13-HMBC (n)J(CH) (n = 2 and 3) and 2D H-1,H-1-NOESY, were utilized. Copyright (C) 2001 John Wiley & Sons, Ltd.