Steric and stereochemical effects on the free-radical bromination of tetracyclic and hexacyclic fragments of the MDR inhibitor N-acetylardeemin

Tetrahedron

Volumn 55, Issue 49, 1999, Pages 14185-14198

  Caballero, Esmeralda ^a   Avendaño, Carmen ^a   Menéndez, J Carlos ^a  

^a UNIVERSIDAD COMPLUTENSE DE MADRID   (Spain)

Author keywords

Elimination reactions; Piperazinones; Quinazolinones; Radicals and radical reactions; Wittig reactions

Indexed keywords

FREE RADICAL; PIPERAZINE DERIVATIVE; QUINAZOLINONE DERIVATIVE;

ARTICLE; BROMINATION; CHEMICAL MODIFICATION; CHEMICAL REACTION; CHEMICAL STRUCTURE; CYCLIZATION; PRIORITY JOURNAL; REACTION ANALYSIS; STEREOCHEMISTRY; STEREOSPECIFICITY;

EID: 0033521105     PISSN: 00404020     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4020(99)00886-8     Document Type: Article

References (21)

1. 1 a) Biological activity: Karwowski, J. P.; Jackson, M; Rasmussen, R. D.; Humphrey, P. E.; Poddig, J. B.; Kohl, W. L.; Scherr, M. H.; Kadam, S.; McAlpine, J. B. J. Antibiotics 1993, 46, 374.
2. b) Isolation and structure: Hochlowski, J.E.; Mullally, M. M.; Spanton, S. G.; Whittern, D. N.; Hill, P.; McAlpine, J. B. J. Antibiotics 1993, 46, 380.
3. c) Total synthesis: Marsden, S. P.; Depew, K. M.; Danishefsky, S. J. Am. Chem. Soc. 1994, 116, 1143.
4. 2 Kane, S. E. Adv. Drug Res. 1996, 28, 181.
5. 3 a) Hodge, R. P.; Harris, C. M.; Harris, T. M. J. Nat. Prod. 1988, 51, 66.
6. b) Arai, K.; Kimura, K.; Mushiroda, T.; Yamamoto, Y. Chem. Pharm. Bull. 1989, 37, 2937.
7. 4 a) Scott, P. M.; Marie-Annick, M.; Polonsky, J. Experientia 1976, 32, 140.
8. b) Chen, W.-C.; Joullié, M. M., Tetrahedron Lett. 1998, 39, 8401.
9. 5 a) Caballero, E.; Avendaño, C.; Menéndez, J. C. Tetrahedron: Asymmetry 1998, 9, 967.
10. b) Caballero, E.; Avendaño, C.; Menéndez, J. C. Tetrahedron: Asymmetry 1998, 9, 3025.
11. 6 See also: Madrigal, A.; Grande, M.; Avendaño, C. J. Org. Chem. 1998, 63, 2724, and references therein.
12. 7 Bruncko, M.; Crich, D.; Samy, R. J. Org. Chem. 1994, 59, 5543.
13. 8 MM2 calculations give a value of 90.4° for the H-C(10b)-C(11)-H dihedral angle.
14. 9 Review on the use of free-radical reactions in the synthesis of aminoacids and their derivatives: Easton, C. J. Chem. Rev. 1997, 97, 53.
15. 10 In the case of the reaction described by Crich, steric hindrance of the tryptophan stereocenter by the side chains of the two neighbouring carboxylate groups probably prevented its bromination. This hindrance is not present in our more rigid starting materials.
16. 11 Easton, C. J.; Hay, M. P.; Love, S. G. J. Chem. Soc., Perkin Trans. I 1988, 265.
17. 12 a) Yoshimura, J.; Nakamura, H.; Matsunari, K. Bull. Chem. Soc. Jpn. 1975, 48, 605.
18. b) Yoshimura, J.; Sugiyama, Y.; Nakamura, H. Bull. Chem. Soc. Jpn. 1973, 46, 2850.
19. 13 See, for instance: March, J., Advanced Organic Chemistry, 4th. Edition, pp. 681-682. John Wiley and Sons, 1992.
20. 14 For a precedent of this type of epimerization on a similar substrate, see reference 5a.
21. 15 In a related observation, mass spectra of compound 14 and the related dibromo derivatives 28 and 31 were identical to those of the corresponding dehydrobromination derivatives (compounds 15, 29 and 32, respectively).