Enantioselective total synthesis of an antitumor antibiotic, vicenistatin, featuring a 20-membered macrocyclic lactam glycoside with the amino sugar vicenisamine, has been achieved. Key reactions in the synthesis of macrolactam aglycone involved Suzuki cross-coupling and Evans asymmetric aldol reaction. Penultimate glycosidation of the O-TMS-aglycone with appropriately protected 1-O-acetyl amino sugar and final deprotection allowed accomplishment of the total synthesis.
A new strategy for the synthesis of 2,6-dideoxyamino sugars from non-sugar starting materials has been developed. The key reaction in this strategy is the acid-catalyzed intramolecular cyclization, by which a nitrogen functional group is introduced with simultaneous control of vicinal chiral centers. The synthesis of two kinds of 2,6-dideoxyamino sugars, D-vicenisamine and L-kedarosamine, by this strategy is described.