The HSQC spectrum permitted the assignment of all carbons via one-bond 13C-1H correlations (Figure S20, Supporting Information). Eight paramagnetically shifted nonanomeric protons were observed, indicating the presence of esterifying groups, and their location on each monomeric unit was identified by the HMBC technique (Figure S21, Supporting Information) as follows: (a) The unit A macrolactonization site was identified at C-2 of the second saccharide unit, due to the observed correlation between the lactone carbon (δC173.1) and H-2 (δH 5.93) of Rha; (b) the ester-type linkage of the aglycone in unit A at the pentasaccharide core of unit B was placed at C-4 (δH4.4) of the terminal glucose of unit
A