Hydrolytically labile ω-chloro-ω-phenylthioglycosides, obtained from the corresponding ω-phenylthioglycosides on treatment with NCS in CCl 4, are readily dealkoxyhalogenated with Zn/Ag-graphite in anhydrous solvents affording enantiomerically pure synthons bearing an aldehyde function at the one end and a vinylthioether group at the other end of the ring-opened product. This fragmentation technique turned out to be general and was used for the synthesis of a building block exhibiting the substitution pattern of the C9C14 segment common to all trienomycin-, mycotrienin, and ansatrienin macrolide antibiotics. Zn/Ag-graphite was also used to reductively ring-open the 6-deoxy-6-iodopyranoside 37, easily accessible from D-glucose, to enal 38, which served as central precursor for the synthesis of both the C1C6 as well as C7C13 unit of the polyhydroxylated chain of amphoteronolide B. Combining these two segments 45 and 51 by ketophosphonate/aldehyde coupling afforded enone 54 which is synthetically equivalent to an intermediate of a former total synthesis of this macrolide. Thus, a convergent synthesis of the C1C13 fragment of amphotericin B based upon the hidden C 2-symmetry of this target molecule was achieved using metal-graphite promoted ring-opening of carbohydrates in the key step in combination with formal inversion of the configuration of the resulting hex-5-enals.