Degenerate racemization of chiral saddle conformations in a cyclic dioxadithia aryl polyether

Journal of Organic Chemistry

Volumn 61, Issue 7, 1996, Pages 2553-2555

  Boros, Eric E ^a   Andrews, C Webb ^a   Davis, Ann O ^a  

^a GLAXOSMITHKLINE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0007436596     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo9515992     Document Type: Article

References (22)

1. Lehmann F., P. A. Tetrahedron 1974, 30, 727-733.
2. Conformational isomers with energy barriers between them of less than ca. 20 kcal/mol are typically inseparable under normal conditions; see reference 3 and (a) Lowry, T. H.; Richardson, K. S. Mechanism and Theory in Organic Chemistry, 2nd ed.; Harper & Row: New York, 1981; pp 115-130. (b) Gilman, N. W.; Rosen, P.; Earley, J. V.; Cook, C.; Todaro, L. J. J. Am. Chem. Soc. 1990, 122, 3969-3978 and references cited therein.
3. Conformational isomers with energy barriers between them of less than ca. 20 kcal/mol are typically inseparable under normal conditions; see reference 3 and (a) Lowry, T. H.; Richardson, K. S. Mechanism and Theory in Organic Chemistry, 2nd ed.; Harper & Row: New York, 1981; pp 115-130. (b) Gilman, N. W.; Rosen, P.; Earley, J. V.; Cook, C.; Todaro, L. J. J. Am. Chem. Soc. 1990, 122, 3969-3978 and references cited therein.
4. For a review of atropisomerism, see: Oki, M. Topics Stereochem. 1983, 14, 1-81.
5. 2b and basic hydrolysis of the oxathiolone moiety, respectively. (a) Umemoto, T.; Fukami, S.; Tomizawa, G.; Harasawa, K.; Kawada, K.; Tomita, K. J. Am. Chem. Soc 1990, 112, 8563-8575. (b) Cresp, T M.; Sargent, M. V. J. Chem. Soc., Perkin Trans. 1 1974, 2145-2153.
6. 2b and basic hydrolysis of the oxathiolone moiety, respectively. (a) Umemoto, T.; Fukami, S.; Tomizawa, G.; Harasawa, K.; Kawada, K.; Tomita, K. J. Am. Chem. Soc 1990, 112, 8563-8575. (b) Cresp, T M.; Sargent, M. V. J. Chem. Soc., Perkin Trans. 1 1974, 2145-2153.
7. 1H NMR. Attempts at further purification by recrystallization and flash chromatography were unsuccessful owing to the poor solubility properties of this compound.
8. (a) Anions of 2-hydroxythiophenols react preferentially at the thiolate position with 2-halonitrobenzenes; see: Martin, G. E.; Turley, J. C.; Williams, L.; Steenberg, M. L.; Buckley, J. P. J. Heterocycl. Chem. 1977, 14, 1067-1069.
9. (b) 2,4-Dihalonitrobenzenes react preferentially at the 2-position with nucleophiles; see: Galbreath, R. J.; Ingham, R. K. J. Org. Chem 1958, 23, 1804-1806 and references cited therein.
10. For a brief discussion of the effects of solvent on chemical shift nonequivalence of prochiral groups, including aromatic solvent induced shift (ASIS), see Jennings, W. B. Chem. Rev. 1975, 75, 307-322.
11. A similar Monte Carlo global conformational search of structure 2 minus the isopropoxy and nitro groups also produced the saddle-shaped arrangement as the global minimum.
12. 2, SPh, and OPh benzene substituent effects are 7.20 and 7.29 ppm, respectively. This indicates similar anisotropic shielding in both systems. For the effects of substituents on the chemical shift of benzene ring protons, see: Pretsch, E.; Clerc, T.; Seibl, J.; Simon, W. In Tables of Spectral Data for Structure Determination of Organic Compounds; Fresenius, W., Huber, J. F. K., Pungor, E., Rechnitz, G. A. Simon, W., West, T. S., Eds.; Springer-Verlag: Berlin, Germany, 1989; pp H255-H260.
13. For examples involving the use of prochiral probes to investigate ring inversion phenomena, see reference 7 and (a) Anet, F. A. L. J. Am. Chem. Soc. 1964, 86, 458-460. (b) Downing, A. P.; Ollis, W. D.; Sutherland, I. O. J. Chem. Soc. (B) 1970, 24-34. (c) Ollis, W. D.; Stoddart, J. F J. Chem. Soc., Chem. Commun. 1973, 571-572.
14. For examples involving the use of prochiral probes to investigate ring inversion phenomena, see reference 7 and (a) Anet, F. A. L. J. Am. Chem. Soc. 1964, 86, 458-460. (b) Downing, A. P.; Ollis, W. D.; Sutherland, I. O. J. Chem. Soc. (B) 1970, 24-34. (c) Ollis, W. D.; Stoddart, J. F J. Chem. Soc., Chem. Commun. 1973, 571-572.
15. For examples involving the use of prochiral probes to investigate ring inversion phenomena, see reference 7 and (a) Anet, F. A. L. J. Am. Chem. Soc. 1964, 86, 458-460. (b) Downing, A. P.; Ollis, W. D.; Sutherland, I. O. J. Chem. Soc. (B) 1970, 24-34. (c) Ollis, W. D.; Stoddart, J. F J. Chem. Soc., Chem. Commun. 1973, 571-572.
16. -ΛGRT; see: Eliel, E. L. Topics Curr. Chem. 1982, 105, 1-76 and references cited therein.
17. UV maxima of 4 were observed at 205, 233, 290, and 363 nm. For the UV absorption spectrum of the 2-nitrophenyl phenyl sulfide chromophore, see: Koch, H. P. J. Chem. Soc. 1949, 387-394
18. Mohamadi, F.; Richards, N. G. J.; Guida, W. C.; Liskamp, R.; Lipton, M.; Caufield, C.; Chang, G.; Hendrickson, T.; Still, W. C. J. Comput. Chem. 1990, 11, 440-467.
19. (a) Allinger, N. L.; Yuh, Y. H.; Lii, J.-H. J. Am. Chem. Soc. 1989, 111, 8551-8566.
20. (b) Lii, J.-H.; Allinger, N. L. Ibid. 1989, 111, 8566-8575.
21. (c) Lii, J.-H.; Allinger, N. L. Ibid. 1989, 111, 8576-8582.
22. Ponders, J. W.; Richards, F. M. J. Comput. Chem. 1987, 8, 1016-1024.