Novel mixed-heteroatom macrocycles via templating: a new protocol

A series of novel thiadiaza and triaza crown ether attached galactose- and glucose-based glycolipids is synthesized, applying a new strategy. The key step is the formation of α-chloroacetamido precursors (14 and 21) from selectively protected bis(cyanomethyl)-glycolipids (13 and 19) in two steps. The cyclization reaction furnishes good yields in relatively short times in aqueous ethanol or acetonitrile. To generalize this method, macrocycles 3 and 25 are reported as well. Attempts to use the traditional synthetic approaches for cyclization failed to provide reasonable yields.