Regioselective aryl radical cyclisation. Part 2.1 Synthesis of octahydro-1H-dibenzo[a,d]cycloheptenes through 7-endo ring closure

Abstract

A simple convergent synthesis of trans- and cis-octahydro-1H-dibenzo[a,d] cycloheptenes 15a–c and 16a–c and 20a–c and 21a–c through implementation of a regioselective 7-endo-trig-aryl radical cyclisation of the respective 2-(o-bromoarylethyl)-1-methylenecyclohexanes 6a–c and 8a–c with tributyltin hydride is described. The scope of the 7-endo aryl radical cyclisation has been further demonstrated by the synthesis of (2SR,4aRS,11aSR)-methyl 1,1-dimethyl-2,3,4,4a,5,10,11,11a-octahydro-1H-dibenzo[a ,d]cycloheptene-2-carboxylate 29.

References

1. Part 1, S. Pal, J. K. Mukhopadhyaya and U. R. Ghatak, J. Org. Chem., 1994, 59, 2687.
2. For bibliography see: C. P. Jasperse, D. P. Curran and T. L. Fevig, Chem. Rev., 1991, 91, 1237; W. B. Motherwell and D. Crich, Free Radical Chain Reactions in Organic Synthesis, Academic Press, London, 1991.
3. (a) M. D. Bachi, F. Frolow and C. Hoornaert, J. Org. Chem., 1983, 48, 1841; (b) A. L. J. Beckwith and D. R. Boate, Tetrahedron Lett., 1985, 26, 1761; (c) D. Wehle, N. Schormann and L. Fitjer, Chem. Ber., 1988, 121, 2171; (d) D. A. Burnett, J. K. Choi, D. J. Hart and Y. M. Tsai, J. Am. Chem. Soc., 1984, 106, 8201; (e) T. Ghosh and H. Hart, J. Org. Chem., 1989, 54, 5073; (f) V. H. Rawat, S. P. Singh, C. Dufour and C. Michoud, J. Org. Chem., 1993, 58, 7718; (g) J. H. Rigby and M. N. Qabar, J. Org. Chem., 1993, 58, 4473; (h) L. Colombo, M. Digiacomo, G. Papeo, O. Carugo, C. Scolastico and L. Manjoni, Tetrahedron Lett., 1994, 35, 4031; (i) S. E. Booth, P. R. Jenkins, C. J. Swain and J. P. Sweeney, J. Chem. Soc., Perkin Trans 1, 1994, 3499; (j) E. Lee, T. S. Kang, B. J. Joo, J. S. Tae, K. S. Li and C. K. Chung, Tetrahedron Lett., 1995, 36, 417; (k) P. A. Evans and J. D. Roseman, J. Org. Chem., 1996, 61, 2252; (l) B. K. Banik, G. V. Subbaraju, M. S. Manhas and A. K. Bose, Tetrahedron Lett., 1996, 37, 1363; (m) G. Rodriguez, M. M. Cid, C. Saa, L. Castedo and D. Dominguez, J. Org. Chem., 1996, 61, 2780.
4. Part of the work was reported in a preliminary communication: A. K. Ghosh, K. Ghosh, S. Pal and U. R. Ghatak, J. Chem. Soc., Chem. Commun., 1993, 809; corrigendum, J. Chem. Soc., Chem. Commun., 1993, 1176.
5. A. L. J. Beckwith and G. Moad, J. Chem. Soc., Chem. Commun., 1974, 472.
6. The cyclisation of oct-7-enyl radical initially reported (ref. 5) as 7-exo-cyclisation has been shown to give only 8-endo product: A. L. J. Beckwith and C. H. Schisser, Tetrahedron, 1985, 41, 3925.
7. D. P. Curran and C. T. Chang, J. Org. Chem., 1989, 54, 3140.
8. D. Batty and D. Crich, Tetrahedron Lett., 1992, 33, 875; D. Batty and D. Crich, J. Chem. Soc., Perkin Trans. 1, 1992, 3193.
9. C. Destabel, J. D. Kilburn and J. Knight, Tetrahedron, 1994, 50, 11 267.
10. B. B. Snider and J. E. Merritt, Tetrahedron, 1991, 47, 8663.
11. A. Ali, D. C. Harrowven and G. Pattenden, Tetrahedron Lett., 1992, 33, 2851.
12. S. Deb, G. Bhattacharjee and U. R. Ghatak, J. Chem. Soc., Perkin Trans. 1, 1990, 1453.
13. A. K. Ghosh, C. Mukhopadhyay and U. R. Ghatak, J. Chem. Soc., Perkin Trans. 1, 1994, 327; G. Majetich, R. Hicks, Y. Zhang, X. Tian, T. L. Feltman, J. Fang and S. Duncan, Jr., J. Org. Chem., 1996, 61, 8169 and references cited therein.
14. S. Ghosh, B. K. Banik and U. R. Ghatak, J. Chem. Soc., Perkin Trans 1, 1991, 3189.
15. U. R. Ghatak, J. Chakravarty and A. K. Banerjee, Tetrahedron, 1968, 24, 1577.
16. J. M. Conia and J. C. Limasset, Bull. Soc. Chem. Fr., 1967, 6, 1936.
17. T. K. M. Shing, V. W.-F. Tai and E. K. W. Tam, Angew. Chem., Int. Ed. Engl., 1994, 33, 2312.
18. F. C. Chang and N. F. Wood, Tetrahedron Lett., 1964, 2969.
19. For a discussion on the stereochemical outcome of various radical cyclisation reactions, see: K. N. Houk, J. Org. Chem., 1987, 52, 959; B. Giese, Angew. Chem., Int. Ed. Engl., 1989, 28, 969; T. V. Rajan Babu, Acc. Chem. Res., 1991, 24, 139; B. Giese, W. Damm, J. Dickhaut, F. Wetterich, D. P. Curran and S. Sun, Tetrahedron Lett., 1991, 32, 6097; J. E. Eksterowicz and K. N. Houk, Tetrahedron Lett., 1993, 34, 427; W. Damm, J. Dickhaut, F. Wetterich and B. Giese, Tetrahedron Lett., 1993, 34, 431; A. L. J. Beckwith, S. P. Joseph and R. T. A. Mayadunne, J. Org. Chem., 1993, 58, 4198; C. F. Sturino and A. G. Fallis, J. Am. Chem. Soc., 1994, 116, 7447.
20. S. S. Shaik and E. Canadell, J. Am. Chem. Soc., 1990, 112, 1446.
21. B. K. Banik, A. K. Chakravarty and U. R. Ghatak, J. Chem. Res., 1986, (S) 406; (M), 3391.