pactamycin and cyclopentanone

This article describes synthetic studies that culminated in the first total synthesis of pactamycin and pactamycate and, in parallel, the two known congeners, de-6-MSA-pactamycin and de-6-MSA-pactamycate, lacking the 6-methylsalicylyl moiety. Starting with L-threonine as a chiron, a series of stereocontrolled condensations led to a key cyclopentenone harboring a spirocyclic oxazoline. A series of systematic functionalizations led initially to the incorrect cyclopentanone epoxide, which was "inverted" under solvolytic conditions. Installation of the remaining groups and manipulation of the oxazoline eventually led to pactamycin, pactamycate, and their desalicylyl analogues.

Topics: Cyclopentanes; Molecular Structure; Pactamycin; Salicylates; Threonine

[structure: see text]. Pactamycin, one of the most complex and densely functionalized aminocyclitol antibiotics known, presents synthetic challenges that include reactivity and sterics, relative and absolute stereochemistry, and functional group compatibility and protection. An approach is reported that features four different types of (cyclopentane) face selective functionalization reactions and results in a polyfunctionalized and appropriately protected intermediate that incorporates all the core carbons and the oxygenated functionality of the target.

Topics: Anti-Bacterial Agents; Cyclopentanes; Molecular Structure; Oxygen; Pactamycin; Stereoisomerism