Combined directed Ortho and remote metalation - cross-coupling strategies. General method for benzo[a]carbazoles and the synthesis of an unnamed indolo[2,3-a]carbazole alkaloid

Organic Letters

Volumn 6, Issue 14, 2004, Pages 2293-2295

  Cai, Xiongwei ^a   Snieckus, Victor ^a  

^a QUEEN S UNIVERSITY   (Canada)

Author keywords

[No Author keywords available]

Indexed keywords

ALKALOID DERIVATIVE; CARBAZOLE DERIVATIVE;

ANTINEOPLASTIC ACTIVITY; ANTIVIRAL ACTIVITY; ARTICLE; CHEMICAL REACTION; CROSS COUPLING REACTION; DRUG SYNTHESIS; SUZUKI REACTION;

ANTINEOPLASTIC AGENTS; ANTIVIRAL AGENTS; CARBAZOLES; CATALYSIS; INDICATORS AND REAGENTS; INDOLE ALKALOIDS; INDOLES; MOLECULAR STRUCTURE; NOSTOC;

EID: 3242670935     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol049780x     Document Type: Article

References (17)

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3. (b) For pyridocarbazole synthesis, see: Gribble, G. W. Synlett 1991, 289.
4. (c) For an excellent, comprehensive review, see: Knolker, H. J.; Reddy, K. R. Chem Rev. 2002, 102, 4303.
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6. Beight, D. W.; Kinnick, M. D.; Lin, H.; Morin, J. M.; Richett, M. E.; Sall, D. J.; Sayer, J. S. US patent WO 2002050034; Chem. Abstr. 2002, 137, 47114.
7. For application of this strategy to phenanthrenes, see: (a) Fu, J.-m.; Snieckus, V. Can. J. Chem. 2000, 78, 905. (b) Cai, X.; Brown, S.; Hodson, P.; Snieckus, V. Can. J. Chem. 2004, 82, 195.
8. For application of this strategy to phenanthrenes, see: (a) Fu, J.-m.; Snieckus, V. Can. J. Chem. 2000, 78, 905. (b) Cai, X.; Brown, S.; Hodson, P.; Snieckus, V. Can. J. Chem. 2004, 82, 195.
9. (a) For the primary routes to benzo[a]carbazoles (Fischer indole, Diels - Alder, Cr, Fe, Mo, and Pd-mediated, photochemical) and their evaluation, see ref 2c. For Rh-catalyzed alkyne cyclotrimerizations, see: Witulski, B.; Alayrac, C. Angew. Chem., Int. Ed. 2002, 41, 3281.
10. (b) For an N-acyliminium approach from ditryptophans with implications for peptide transformations in vivo, see: Carter, D. S.; Van Vranken, D. L. J. Org. Chem. 1999, 64, 8537.
11. 13NO, 247.0997, found 247.0997.
12. For the preparation of enol triflates, see: Crisp, G. T.; Scott, W. J. Synthesis 1985, 335.
13. Prepared in 82% yield by NBS bromination of N,N-diethylindole-3- carboxamide, see: Mistry, A. G.; Smith, K.; Bye, M. R. Tetrahedron Lett. 1986, 27, 1051.
14. Hudkins, R. L.; Diebold, J. L.; Marsh, F. D. J. Org. Chem. 1995, 60, 6218.
15. 1 mp > 280°C dec). IR and NMR are identical to those reported. For details, see the Supporting Information.
16. For previous syntheses, see: Hayashi, H.; Ohmoto, S.; Somei, M. Heterocycles 1997, 45, 1647 (two routes from indigo in 13% (six steps) and 5% (seven steps) overall yields respectively both of which involve a terminal nonregioselective N-methylation): Hayashi, H.; Suzuki, Y.; Somei, M. Heterocycles 1999, 51, 1233 (from indigo in 59% (six steps) overall yield). All routes involve interesting key central-ring closures via potentially electrocyclic processes, an anionic version of which for the cyclization of 15 may also be contemplated.
17. For previous syntheses, see: Hayashi, H.; Ohmoto, S.; Somei, M. Heterocycles 1997, 45, 1647 (two routes from indigo in 13% (six steps) and 5% (seven steps) overall yields respectively both of which involve a terminal nonregioselective N-methylation): Hayashi, H.; Suzuki, Y.; Somei, M. Heterocycles 1999, 51, 1233 (from indigo in 59% (six steps) overall yield). All routes involve interesting key central-ring closures via potentially electrocyclic processes, an anionic version of which for the cyclization of 15 may also be contemplated.