Total synthesis of methymycin.

Methynolide and 10-epi-methynolide were synthesized from the necessary segments, which were prepared by the addition of Grignard reagents to the corresponding alpha-alkoxyketones utilizing 1,2-stereochemical selection based on Cram chelation control. Ring-closing metathesis, as the key reaction, was carried out to combine the segments for the synthesis of methynolide and 10-epi-methynolide. The total synthesis of methymycin was also achieved by the glycosylation of methynolide with the trichloroimidate derivative of D-desosamine.