Novel Tandem Reaction for the Synthesis of N′‐Substituted 2‐Imino‐1,3‐oxazolidines from Vicinal (sec‐ or tert‐)Amino Alcohol of Desosamine

Two one-pot methods, sequential and tandem, for the preparation of N'-substituted 2-imino-1,3-oxazolidines from the vicinal (sec-or tert)-amino alcohol of desosamine via intermediary alkyl-, aryl-, heteroaryl-, and heteroalkyl-thiourea moieties are described. Particularly interesting is the novel one-pot tandem reaction of the vicinal tert-amino alcohol that involves dealkylation, thiourea formation, and a final cyclization to yield 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-membered macrolides was prepared to demonstrate the variety of substituents that can be easily introduced and thus enable a huge variation of the physico-chemical and hence biological properties of these new molecules.