Dithioacetals of sugars provide useful starting materials for synthesis of various deoxy sugar derivatives by way of polythio intermediates, and also afford convenient access to acyclic aldose derivatives having two different substituents at C-i. The conformations of aldose diethyl and diphenyl dithioacetals in solution, as determined by p.m.r. spectroscopy with the aid of lanthanide salts, fol...