ChemInform Abstract: Studies on Glycosylation of erythro-β-Hydroxy-L-histidine. A Key Step of Bleomycin Total Synthesis.
Abstract
To improve the synthetic yield of bleomycin and its analogues, a study has been undertaken to find the high-yield procedure for condensation of the sugar portion with the hydroxyl group of the erythro-β-hydroxy-L-histidine moiety, preventing the N-glycosylation to imidazole.
ChemInform Abstract
To improve the synthetic yield of bleomycin and its analogues, a study has been undertaken to find the high-yield procedure for condensation of the sugar portion with the hydroxyl group of the erythro-β-hydroxy-L-histidine moiety, preventing the N-glycosylation to imidazole. For this purpose, condensation reactions of the histidine derivatives (lb)-(ld) [each obtainable from (Ia)] with the bro- I86 mides (II) or (IX) are carried out (cf. scheme). The best yields of product are obtained from the reactions of (Ic) with (II) or (IXb) [- (VII), (Xa)], and this result reveals that 1. thg?im-tqsyl group is the most effective in preventing the Nim-glycosylation [e.g.
