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A study of vinyl radical cyclization using N-alkenyl-7-bromo-substituted hexahydroindolinones

  • Albert Padwa*
  • , Paitoon Rashatasakhon
  • , Ayse Daut Ozdemir
  • , Jerremey Willis
  • *Bu çalışma için yazışmadan sorumlu yazar

Araştırma sonucu: Dergiye katkıMakalebilirkişi

36 Atıf (Scopus)

Özet

(Chemical Equation Presented) A new method for the synthesis of the octahydropyrrolo[3,2,1-ij]quinoline ring system that possesses the characteristic skeleton of the aspidosperma family of alkaloids has been developed. The method utilizes an intramolecular Diels-Alder reaction of an amido-substituted furan across a tethered indole π-bond. To apply this strategy to the synthesis of the indole alkaloid spegazzinidine, it was necessary to address the problem of assembling the final D-ring of the pentacyclic skeleton. Radical cyclization of a model N-allyl-7-bromo-3a- methylhexahydroindolinone system was found to preferentially lead to the 6-endo-trig cyclization product, with the best yield being obtained under high dilution conditions. The six-membered cyclized product is generated through two reaction pathways: (a) 6-endo-trig ring closure and (b) rearrangement of an intermediate methylene-cyclopentyl radical obtained by 5-exo-trig cyclization. A number of related 7-bromo-substituted hexahydroindolinones containing tethered olefinic groups were prepared and found to undergo efficient cyclization under both radical and palladium-mediated reaction conditions. Vinyl radical cyclization with several N-butenyl-substituted systems afforded a mixture of 6-exo and 7-endo cyclization products. A protocol to introduce an ethyl substituent into the C20-position of the aspidospermidine skeleton was also developed.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)519-528
Sayfa sayısı10
DergiJournal of Organic Chemistry
Hacim70
Basın numarası2
DOI'lar
Yayın durumuYayınlandı - 21 Oca 2005
Harici olarak yayınlandıEvet

Finansman

FinansörlerFinansör numarası
National Center for Research ResourcesS10RR013673

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