The condensation of the protected aglucone (I) with the glucoside (II) by means of TBS triflate gives the condensed alpha-glucoside (III), which is worked up to yield the bis-chloroacetylated intermediate that is desilylated to compound (IV). The condensation of (IV) with disaccharide (V) gives the trisaccharide (VI), which by deprotection of the phenolic chloroacetate and condensation with disaccharide (VII) affords the pentasaccharide (VIII).
The elimination of the diol protecting group of compound (VIII) with CSA in methanol followed by silylation with TES triflate affords the silylated pentasaccharide (IX), which is finally desulfurized and deiodinated by hydrogenolysis with Et3B and Bu3SnH, and with RaNi to eliminate also the BOM protecting group, and with FH in pyridine to eliminate the silyl and chloroacetyl groups affording the target olivomycin A.