An interesting approach for the chemo-enzymatic synthesis of carbohydrates is the use of glycosynthases, a class of mutant glycosidases derived from $beta$-glycoside hydrolases obtained by replacement of the active site nucleophile with a non-nucleophilic residue. However, the scarcity of $alpha$-glycosynthases has so far hampered access to the synthesis of a large class of oligosaccharides of biotechnological interest. We review here a new glycosynthetic methodology for the production of two retaining $alpha$-fucosynthases and an $alpha$-galactosynthase exploiting $beta$-glycosyl azide derivatives. The general applicability of this approach, which opens new perspectives in the use of azide derivatives for the production of novel $alpha$-glycosynthases, is discussed.