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Diazonamide synthetic studies. Reactivity of N-unsubstituted benzofuro[2,3-b]indolines

Benzofuro[2,3-b]indolines undergo ring opening in the presence of base to generate 3H-indolines. The latter can rearrange into 3-arylindoles through an intramolecular transfer of the methoxycarbonyl moiety from quaternary carbon to oxygen of phenol. The intermediate 3H-indolines can be isolated upon DMAP-catalyzed O-acylation of the phenol moiety with Boc2O.

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  1. * Isolated compound 11a was converted to N-deprotected indole 8a under thermal conditions (PhMe, 160°C, 30 min)8 to confirm the structural assignment for compound 8a, which was based on the NMR experiments.

  2. * As has been demonstrated by Hassner,9 the reaction of DMAP with Boc2O produces ion pair: N-Boc-pyridinium tert-butoxycarboxylate. The tert-butoxycarboxylate decomposes to CO2 and the strong base tert-butoxide.


  1. For review on synthesis of diazonamide A, see: Lachia, M.; Moody, C. Nat. Prod. Rep. 2008, 25, 227.

  2. Cruz-Monserrate, Z.; Vervoort, H. C.; Bai, R.; Newman, D. J.; Howell, S. B.; Los, G.; Mullaney, J. T.; Williams, M. D.; Pettit, G. R.; Fenical, W.; Hamel, E. Mol. Pharmacol. 2003, 63, 1273.

    CAS  Article  Google Scholar 

  3. For review, see: Beaud, R.; Tomakinian, T.; Denizot, N.; Pouilhès, A.; Kouklovsky, C.; Vincent, G. Synlett 2015, 26, 432.

  4. (a) Tomakinian, T.; Kouklovsky, C.; Vincent, G. Synlett 2015, 26, 1269. (b) Ding, H.; DeRoy, P. L.; Perreault, C.; Larivée, A.; Siddiqui, A.; Caldwell, C. G.; Harran, S.; Harran, P. G. Angew. Chem., Int. Ed. 2015, 54, 4818. (c) Tomakinian, T.; Guillot, R.; Kouklovsky, C.; Vincent, G. Angew. Chem., Int. Ed. 2014, 53, 11881. (d) Liao, L.; Shu, C.; Zhang, M.; Liao, Y.; Hu, X.; Zhang, Y.; Wu, Z.; Yuan, W.; Zhang, X. Angew. Chem., Int. Ed. 2014, 53, 10471. (e) Shu, C.; Liao L.-H.; Liao Y.-J.; Hu, X.-Y.; Zhang, Y.-H.; Yuan, W.-C.; Zhang, X.-M. Eur. J. Org. Chem. 2014, 4467. (f) Denizot, N.; Pouilhès, A.; Cucca, M.; Beaud, R.; Guillot, R.; Kouklovsky, C.; Vincent, G. Org. Lett. 2014, 16, 5752. (g) Zhao, J.-C.; Yu, S.-M.; Liu, Y.; Yao, Z.-J. Org. Lett. 2013, 15, 4300. (h) Beaud, R.; Guillot, R.; Kouklovsky, C.; Vincent, G. Angew. Chem., Int. Ed. 2012, 51, 12546.

  5. (a) Zajac, M. A.; Vedejs, E. Org. Lett. 2004, 6, 237. (b) Peris, G.; Vedejs, E. J. Org. Chem. 2015, 80, 3050.

  6. Poriel, C.; Lachia, M.; Wilson, C.; Davies, J. R.; Moody, C. J. J. Org. Chem. 2007, 72, 2978.

    CAS  Article  Google Scholar 

  7. Mutule, I.; Joo, B.; Medne, Z.; Kalnins, T.; Vedejs, E.; Suna, E. J. Org. Chem. 2015, 80, 3058.

    CAS  Article  Google Scholar 

  8. Rawal, V. H.; Cava, M. P. Tetrahedron Lett. 1985, 26, 6141.

    CAS  Article  Google Scholar 

  9. Basel, Y.; Hassner, A. J. Org. Chem. 2000, 65, 6368.

    CAS  Article  Google Scholar 

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We thank European Social Fund (project No. 1DP/ for financial support of this research. E. Vedejs thanks InnovaBalt project for funding.

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Correspondence to Edgars Suna.

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Published in Khimiya Geterotsiklicheskikh Soedinenii, 2015, 51(7), 613–620

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Mutule, I., Kalnins, T., Vedejs, E. et al. Diazonamide synthetic studies. Reactivity of N-unsubstituted benzofuro[2,3-b]indolines. Chem Heterocycl Comp 51, 613–620 (2015).

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  • diazonamide
  • DMAP
  • hemiaminal
  • indole
  • 3H-indoline