A new general approach to the stereospecific synthesis of 3-hetero subsaturated-2,3,6-tridesoxy sugars is described. Rhamnose and fucose are initially converted to 2,3-unsaturated five and six membered lactone derivatives. After coupling the residual hydroxyl group of the lactose with the reagent A-B-Y-Z (Y atom to be introduced), intramolecular conjugate addition to the unsaturated lactone is performed. Since the residual hydroxyl group is the control point, introduction of the Y-hetero atom occurs in a stereospecific manner. Cleavage of the A, B and Z functionalities attached to the Y atom and reduction of the lactose to a lactol completes the sugar synthesis. Use of sugars with a Beta-alkyl substituent on the unsaturated lactone permits synthesis of 3-alkyl substituted 3-hetero substituted-2,3 tridesoxy sugars. Advantages to the described approach are that all the configurational isomers of a 2,6-didesoxy-3-Y-4-OH substituted sugar can be prepared. Moreover, the methodology is brief, stereospecific, and does not require extensive functional group manipulation. The strategy will be used to synthesize the biologically important amino sugars, daunosamine, acosamine, ristosamine, angolosamine and vancosamine which have been isolated by hydrolysis of various antibiotics.