Pseudomonas viscosa

The antibiotic viscosin from Pseudomonas viscosa (Scheme 8) is a cyclo-depsipeptide acyl-ated at the N-terminus with D-3-hydroxydecanoic add.[103 112] The C-terminal carboxy group is esterified with the hydroxy group of the Thr3 residue. The synthesis of this natural product presents the problem of an ester ring closure and was performed in two steps with initial solid-phase synthesis of the Thr3-0-branched linear intermediate followed by ring closure with formation of the amide bond.1 131... 

A peptidolipid exhibiting antibiotic properties against mycobacteria and viruses produced by Pseudomonas viscosa was obtained as a crystalline compound of m.p. 270-273 °C, [a]o — 168° (ethanol). The N-3d-hydroxydecanoyl-hexapeptide structure (49) proposed originally (118) was later shown to be incorrect because the synthetic product was different from natural viscosin (119). 

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