In order to optimize Mukaiyama reagent-induced cyclization of vicinal sec-amino alcohols of desosamine origin towards exclusive formation of N′-substituted-2-imino-1,3-thiazolidines via a thiocarbamoyl intermediate, the influence of reaction conditions was studied. A novel, mild, one-pot, two-step method was developed, and the formation of N′-substituted-2-imino-1,3-oxazolidines as side products was
2-imino-1, 3-oxazolidine structures. The yields of both one-pot methods are comparable to the yield of the sequential reaction. A small library of a new class of desosamine-modified 14- and 15-memberedmacrolides was prepared to demonstrate the variety of substituents that can be easily introduced and thus enable a huge variation of the physicochemical and hence biological properties of these new molecules