Polarity Controlled Reversal of 5-Exo/6-endo-Selectivities in the Synthesis of β-Brominated Cyclic Ethers

Abstract

Polar bromocyclizations of bishomoallylic alcohols (nucleophilic oxygen), which have methyl and/or phenyl substituents located at positions 1, 4, and/or 5, and cyclizations of the derived alkenoxyl radicals (electrophilic oxygen) followed by bromine atom trapping from BrCCl₃, proceed with complementary regio­selectivities.

Key words

alkoxyl radical - bromide oxidation - tert-butyl hydro­peroxide - Mitsunobu reaction - vanadium

References

• 1a Bartlett PA. In Asymmetric Synthesis   Vol. 3:  Morrison JD. Academic Press; New York: 1984.  p.411 
• 1b Harmange J.-C. Figadère B. Tetrahedron: Asymmetry  1993,  4:  1711 
• 2a Hartung J. Greb M. Tetrahedron Lett.  2003,  44:  6091 
• 2b González IC. Forsyth CJ. J. Am. Chem. Soc.  2000,  122:  9099 
• 2c Hart DJ. Leroy V. Merriman GH. Young DGJ. J. Org. Chem.  1992,  57:  5670 
• 2d Corey EJ. Ha D.-C. Tetrahedron Lett.  1988,  29:  3171 
• 3a Blunt JW. Cropp BR. Munro HG. Northcote PT. Prinsep MR. Nat. Prod. Rep.  2003,  20:  1 
• 3b Faulkner DJ. Nat. Prod. Rep.  2002,  19:  1 
• 4 Hoveyda AH. Evans DA. Fu GC. Chem. Rev.  1993,  93:  1307 
• 5 Hartung J. Kopf TM. Kneuer R. Schmidt P. C. R. Acad. Sci. Paris, Chimie/Chemistry  2001,  649 
• 6 Hartung J. Kneuer R. Eur. J. Org. Chem.  2000,  1677 
• 7 Jones MJ. Moad G. Rizzardo E. Solomin DH. J. Org. Chem.  1989,  54:  1607 
• 8 Hartung J. Gottwald T. pehar K. Synthesis  2002,  1469 
• 9 Hartung J. Kneuer R. Laug S. Schmidt P. pehar K. Svoboda I. Fuess H. Eur. J. Org. Chem.  2003,  4033 
• 10a Mitsunobu O. Synthesis  1981,  1 
• 10b Hughes DL. Org. React.  1992,  42:  335 
• 11 Hartung J. Gottwald T. Kneuer R. Synlett  2001,  749 
• 12 Greb, M.; Hartung, J.; Köhler, F.; pehar, K.; Kluge R.; Csuk, R., manuscript in preparation. This procedure has been applied in ref. and in: Hartung J. Kunz P. Laug S. Schmidt P. Synlett  2003,  51 
• 13 Hartung J. Gottwald T. pehar K. Synlett  2003,  227 
• 14 Hartung J. In Radicals in Organic Synthesis   Vol. 2:  Renaud P. Sibi MP. Wiley-VCH; Weinheim: 2001.  p.427 
• 15 Hartung J. Hertel B. Trach F. Chem. Ber.  1993,  126:  1187 
• 16 Wentrup C. In Reaktive Zwischenstufen   Vol. 1:  Thieme; Stuttgart: 1979.  p.63 
• 17 Dupuis J. Giese B. Rüegge D. Fischer H. Korth HG. Sustmann R. Angew. Chem., Int. Ed. Engl.  1984,  23:  896 
• 18 Damm W. Giese B. Hartung J. Hasskerl T. Houk KN. Hüter O. Zipse H. J. Am. Chem. Soc.  1992,  114:  4067 
• 19 Hartung J. Hiller M. Schmidt P. Liebigs Ann.  1996,  1425 
• 20 Fleming I. Grenzorbitale und Reaktionen Organischer Verbindungen   VCH; Weinheim: 1979.  p.141 
• 21 Barton DHR. Crich D. Kretzschmar G. J. Chem. Soc., Perkin Trans. 1  1986,  39