(2E,10E,12E)-(4S,5S,6S,8R,14S,15R)-5-(tert-Butyl-dimethyl-silanyloxy)-4,6,8,14-tetramethyl-9-oxo-15-(tetrahydro-pyran-2-yloxy)-heptadeca-2,10,12-trienoic acid methyl ester

protomycinolide IV

(3E,11E,13E)-(5S,6S,7S,9R,15S,16R)-6-(tert-Butyl-dimethyl-silanyloxy)-16-ethyl-5,7,9,15-tetramethyl-oxacyclohexadeca-3,11,13-triene-2,10-dione