Cyclization of 1-(carbamoyl)dichloromethyl radicals upon activated alkenes. A new entry to 2-azabicyclo[3.3.1]nonanes

Tetrahedron Letters

Volumn 38, Issue 39, 1997, Pages 6901-6904

  Quirante, Josefina ^a   Escolano, Carmen ^a   Costejà, Laura ^a   Bonjoch, Josep ^a  

^a UNIVERSITY OF BARCELONA   (Spain)

Author keywords

[No Author keywords available]

Indexed keywords

ALKENE DERIVATIVE; BICYCLO[3.3.1]NONANE DERIVATIVE; RADICAL;

ACETYLATION; ARTICLE; CHEMICAL REACTION; CYCLIZATION; DRUG SYNTHESIS; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; REACTION ANALYSIS;

EID: 0030848012     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(97)01590-6     Document Type: Article

References (25)

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2. (b) Quirante, J.; Escolano, C.; Bosch, J.; Bonjoch, J. J. Chem. Soc., Chem. Commun. 1995, 2141-2142.
3. (c) Quirante, J.; Escolano, C.; Massot, M.; Bonjoch, J. Tetrahedron 1997, 53, 1391-1402.
4. For the synthesis of five-membered rings from trichloroacetamides, see: (a) Nagashima, H.; Wakamatsu, N.; Ozaki, N.; Ishii, T.; Watanabe, M.; Tajima, T.; Itoh, K. J. Org. Chem. 1992, 57, 1682-1689.
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8. (e) For a related process, in which a cyclization of a trichloroacetamide occurs upon a phenol ring, using Ni as a promoter, see: Bovin, J.; Yousfi, M.; Zard, S. Z. Tetrahedron Lett. 1994, 35, 9553-9556.
9. For the synthesis of four-membered rings from trichloroacetamides, see: Quiclet-Sire, B.; Saunier, J.-B.; Zard, S. Z. Tetrahedron Lett. 1996, 37, 1397-1400.
10. To our knowledge this type of cyclization has not been precedented. Alkyl radicals usually do not react with silyl enol ethers: Urabe, H.; Kuwajima, I. Tetrahedron Lett. 1986, 27, 1355-1358. For the use of (ethoxymethoxy)alkenes as radical acceptors, see: Knapp, S.; Gibson, F. S. J. Org. Chem. 1992, 57, 4802-4809.
11. To our knowledge this type of cyclization has not been precedented. Alkyl radicals usually do not react with silyl enol ethers: Urabe, H.; Kuwajima, I. Tetrahedron Lett. 1986, 27, 1355-1358. For the use of (ethoxymethoxy)alkenes as radical acceptors, see: Knapp, S.; Gibson, F. S. J. Org. Chem. 1992, 57, 4802-4809.
12. The 2-azabicyclo[3.3.1]nonane framework constitutes a structural subunit of many types of alkaloids. Methods inducing the ring closure of this heterocyclic system are of great interest for the development of synthetic approaches to natural products which embody this nucleus.
13. It is known that electrophilic radicals have an ambiphilic behaviour with alkenes: Curran, D. P.; Eichenberger, E.; Collis, M.; Roepel, M. G.; Thoma, G. J. Am. Chem. Soc. 1994, 116, 4279-4288.
14. For retrosynthetic planning using radical reactions, see: Curran, D. P. Synlett 1991, 63-72.
15. 13C NMR spectra, as well as appropiate parent ion identification by HRMS. In addition, compounds 1a, 1b, 4c, 5a 5c, 6a, 6b, and 7b gave satisfactory combustion analysis.
16. 2, rt, 80% yield) followed by hydrolysis of the acetal moiety (3 N HCl, THF, rfx, 71%).
17. (a) Johnson, S.J. J.Org. Chem. 1995, 60, 8089-8092.
18. (b) Quirante, J.; Escolano, C.; Bonjoch, J. Synlett 1997, 196-197.
19. 2Ph), 7.21-7.31 (m, 5 H, ArH).
20. 2Ph), 7.24-7.34 (m, 5 H, ArH).
21. 2Ph), 7.20-7.30 (m, 5 H, ArH).
22. Miller, R. D.; Mckean, D. R. Synthesis 1979, 730-732.
23. For a related process, see: Giese, B.; Horler, H.; Leising, M. Chem. Ber. 1986, 119, 444-452.
24. IV compounds, upon silyl enol ethers, see: Kohno, Y.; Narasaka, K. Chem. Lett. 1993, 1689-1692.
25. Damm, W.; Giese, B.; Hartung, J.; Hasskerl, T.; Houk, K. N.; Hüter, O.; Zipse, H. J. Am. Chem. Soc. 1992, 114, 4067-4079.