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Synthetic studies on prostaglandins: "synthesis of a new thia-PGEI analog"

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Show simple item record Ratemi, Elaref S. en_US 2009-07-09T18:43:12Z 2009-07-09T18:43:12Z 1992-07-09T18:43:12Z
dc.description.abstract A PGE1 analog, namely (±)-trans-2-(6'-carbomethoxyhexyl)-3- (E-3"-thia-1 "-octene)-4-hydroxycyclopentanone 71, has been prepared for the first time. Towards the synthesis of this compound, several synthetic approaches aimed at the preparation of the required acetylenic and E-halovinylic sulfides as building blocks were investigated. Among all the methods examined, it appeared evident that the best route to ethynyl n.pentyl sulfide 81 is via a double dehydrohalogenation of the corresponding 1,2-dibromoethyl sulfide with sodium amide in liquid ammonia. In addition, the isomerically pure E-2-iodoethenyl n.pentyl sulfide 85 is conveniently prepared in high yield and stereoselectivity by hydrozirconation-iodination of the terminal ethynyl sulfide 81. The classical hydroalumination and hydroboration reactions for the preparation of vinyl halides from alkynes gave only small yields when applied as methods towards the synthesis of 85 . The building block 2-(6'-carbomethoxyhexyl)-4-hydroxy-2- cyclopentenone (±)-1 carrying the upper side-chain of prostaglandin E 1 was prepared by a step-wise synthesis involving transformations of compounds possessing the required carbocyclic framework (see scheme 27). The synthesis proved to be convenient and gave a good overall yield of (±)-1 which was protected as the TH P-derivative 37 or the siloxy derivative 38. With the required building blocks 81 and 37 in hand, the target 1S-thia-PGE1 analog (±)-71 was prepared via the in situ higher cuprate formation-conjugate addition reaction. This method proved to be convenient and stereospecific. The standard cuprate method, involving an organocuprate reagent generated from an isolated vinyl iodide, did not work well in our case and gave a complicated mixture of products. The target compound will be submitted for assessment of bio log ical activity. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Prostaglandins--Synthesis. en_US
dc.subject Synthetic prostaglandins E. en_US
dc.subject Prostaglandins E. en_US
dc.title Synthetic studies on prostaglandins: "synthesis of a new thia-PGEI analog" en_US
dc.type Electronic Thesis or Dissertation en_US M.Sc. Chemistry en_US Masters en_US
dc.contributor.department Department of Chemistry en_US Faculty of Mathematics and Science en_US

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