Synthesis of 3-deoxy-3,4-didehydro derivatives of 5-O-mycaminosyltylonolide, 5-O-(4-deoxymycaminosyl) tylonolide, and desmycosin.

The 3-deoxy-3,4-didehydro derivatives of 5-O-mycaminosyltylonolide, 5-O-(4-deoxymycaminosyl)tylonolide, and desmycosin have been prepared by treatment of the corresponding 3-O-sulfonyl derivatives with NaI in 2-butanone as the key step. The mechanistic difference in the formation of the 2,3- and 3,4-unsaturated derivatives from the same 3-O-sulfonyl derivative is discussed.