Enantiomeric synthesis of endo-substituted tetrahydropyrans

✍ Scribed by Victor S Martín; Maria T Nuñez; Miguel A Ramirez; Marcos A Soler

• Publisher: Elsevier Science
• Year: 1990
• Tongue: French
• Weight: 212 KB
• Volume: 31
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)94623-9

✦ Synopsis

A geneml pmcedm for the enantiometic gnthesis of 3-hydmy-2-aQkbuhydm~ benmates with absolute stemxhemical conbvl by using a new intramolecular diartervoselective tydtion of chid hy&vxy-a,w unswd &em is nported In our general program devoted to the total synthesis of bioactive marine natural products') we have directed our attention to a wide group of substances isdated from different species of Luumuia, as well as fromA&ia mdluscs, which have In common the presence of polyfunctionalized cyclic ethers,%which are also the main structural feature of a group of very complex mdecules presenting a strong toxic effect and which are produced by different microorganisms, mainly dinofkgetlates, from which the brevetoxlnr have undoubtedly received more attention than any of the others, over the last decade?) Brevetoxin A-m)

The main probfem to sofve in any total synthesis of this kind of substances in their enantlomeric natural form is the proper building up of a suitable cyclic ether with sufficient functionality to join all the other rings.

We have focus& our attention on the compounds containing the tetrahydropyran moiety, continuing our basic approach In the synthesfs of polysubsttuted tetrahydrofurans,of first con&uctlng a suitable acydk precursorwhkh is further submftted to stereosdecttve cydizatkn .'I However, In the synthesis of substftuted tetrahydropyrans a major dfffkufty arises with this approach, In the sense thatatleastspeclalstructuralfeaturesareintroduced," Inacyclizatlonolanacyclkchainlthesmallerringkproducedwhen the ew-and en&openings are competing (tetrahydrofuran 1 vs. tetrahydropyran 2). according to Baldwin's rufes.@ 763 -