Novel modifications of the desosamine sugar of 14-and 15-membered antibacterial macrolides, in which the desosamine was fused with N-substituted-1, 3-oxazolidin-2-ones, were developed in order to completely suppress antibacterial activity and make them promising agents for other biological targets. The synthesis of such bicyclic desosamine derivatives, especially 1, 3-oxazolidin-2-one formation, was optimized and conducted ...