Toward the synthesis of reidispongiolide a: stereocontrolled synthesis of the C17-C22 and C23-C35 degradation fragments

Structure determination, correction, and disproof of marine macrolide natural products by chemical synthesis

Integration of chemical synthesis, NMR spectroscopy, and various analytical means is key to success in the structure elucidation of stereochemically complex marine macrolide natural products.

Studies on the Synthesis of Reidispongiolide A: Stereoselective Synthesis of the C(22)-C(36) Fragment

A highly stereoselective synthesis of the C(22)-C(36) fragment 2 of reidispongiolide A is described. This synthesis features the highly stereoselective mismatched double asymmetric crotylboration reaction of the aldehyde derived from 5 and the new chiral reagent (S)-(E)-7 that provides 12 with >15:1 d.r. Subsequent coupling of the derived vinyl iodide 3 with aldehyde 16 provided allylic alcohol 17, that was elaborated by three steps into the targeted reidispongiolide fragment 2.

Recent Advances in the Total Synthesis of Polyketide Natural Products as Promising Anticancer Agents

A growing number of complex polyketides, isolated from a variety of marine and terrestrial sources, present novel scaffolds for the development of cancer therapeutic agents. However, the low natural abundance of such lead compounds often precludes full biological evaluation, which demands the development of efficient synthetic routes to afford a sustainable supply. In this account, we provide an overview of the total synthesis of several representative anticancer polyketides – dolastatin 19, spirangien A, reidispongiolide A, and spongistatin 1/altohyrtin A – based on versatile aldol methodology developed in our group.

Total synthesis of (-)-reidispongiolide A, an actin-targeting macrolide isolated from the marine sponge Reidispongia coerulea

A stereocontrolled total synthesis of the microfilament-destabilizing cytotoxic macrolide (-)-reidispongiolide A, isolated from the New Caledonian marine sponge Reidispongia coerulea, is described. This synthesis utilizes a convergent aldol-based strategy to construct the 26-membered macrolactone, followed by the late-stage coupling of a derived aldehyde with an N-vinylformamide-containing ketone subunit to install the full side chain. Two alternative routes were examined for the introduction of the 2E,4E-dienoate region, and a complex Mukaiyama aldol coupling was used to connect the northern and southern hemispheres to install the C13 stereocenter. This constitutes the first chemical synthesis of any member of the reidispongiolide/sphinxolide family of marine macrolides and unequivocally establishes the relative and absolute configuration.

The stereocontrolled total synthesis of altohyrtin A/spongistatin 1: the CD-spiroacetal segment

Stereocontrolled syntheses of the C16-C28 CD-spiroacetal subunit of altohyrtin A/spongistatin 1 , relying on kinetic and thermodynamic control of the spiroacetal formation, are described. The kinetic control approach resulted in a slight preference (60 : 40) for the desired spiroacetal isomer. The thermodynamic approach allowed ready access to the desired spiroacetal by acid-promoted equilibration, chromatographic separation of the C23 epimers and resubjection of the undesired isomer to the equilibration conditions. This scalable synthetic sequence provided multi-gram quantities of , thus enabling the successful completion of the total synthesis of altohyrtin A/spongistatin 1, as reported in Part 4 of this series.

Synthesis of antimicrofilament marine macrolides: synthesis and configurational assignment of a C5-C16 degradation fragment of reidispongiolide A

Reidispongiolide A is a representative member of the sphinxolide/reidispongiolide group of cytotoxic 26-membered macrolides of marine origin. By interacting with actin in the cell cytoskeleton, the reidispongiolides and sphinxolides are potent microfilament destabilizing agents that represent a promising mechanism of action for developing novel anticancer drugs. An aldol-based synthesis of a library of diastereomers of C(8)-C(16) and C(5)-C(16) fragments and detailed NMR comparison with a reported degradation fragment enabled a configurational assignment for a major part of the reidispongiolide macrocyclic core, thus setting a solid foundation for ongoing synthetic efforts.