An Entry to the Azocino[4,3-b]indole Framework through a Dehydrogenative Activation of 1,2,3,4-Tetrahydrocarbazoles Mediated by DDQ: Formal Synthesis of (+/-)-Uleine


Patir S., Erturk E.

JOURNAL OF ORGANIC CHEMISTRY, cilt.76, ss.335-338, 2011 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 76 Konu: 1
  • Basım Tarihi: 2011
  • Doi Numarası: 10.1021/jo1021663
  • Dergi Adı: JOURNAL OF ORGANIC CHEMISTRY
  • Sayfa Sayıları: ss.335-338

Özet

It is presented that hexahydro-1,5-methano[4,3-b]indoles were efficiently synthesized in high yields (up to 89% yield) through the cyclization reaction of starting tetrahydrocarbazoles bearing a monoalkylaminocarbonylmethyl moiety at the C-2 position mediated by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ). A mechanistic proposal is also given that mainly includes two cascade reactions: (i) formation of a vinylogous iminium cation via DDQ-mediated dehydrogenation of tetrahydrocarbazole functionality and (ii) intra-molecular and syn-selective addition of the amide functionality as the nucleophile to the vinylogous iminium cation. Furthermore, this cyclization reaction was successfully utilized in the formal total synthesis of (+/-)-uleine, an Aspidospermatan skeletal type alkaloid.