Intramolecular Tishchenko reactions of protected hexos-5-uloses: a novel and efficient synthesis of L-idose and L-altrose

Protected t-butyl eaters of aldonic acids with the rare L-ido and L-altro c onfiguration can be effectively obtained by a diastereoselective Tishchenko reaction of hexos-5-uloses induced by t-BuOSmI2. These compounds can be ea sily converted into the corresponding protected lactones and free sugars.