Formation of functionalized cyclic ethers by intramolecular nitrile oxide cycloadditions

Albert Padwa, Ugo Chiacchio, Dennis C. Dean, Allen M. Schoffstall, Alfred Hassner, K. S.K. Murthy

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The reaction of O-trimethylsilyl α-bromo aldoximes with unsaturated alcohols produces oximino ethers which can be readily oxidized with sodium hypochlorite. The transient nitrile oxide intermediate formed undergoes spontaneous cyclization affording fused isoxazolines. MM2 calculations help rationalize the observed stereoselectivity.

Original languageEnglish
Pages (from-to)4169-4172
Number of pages4
JournalTetrahedron Letters
Volume29
Issue number33
DOIs
StatePublished - 1988

Bibliographical note

Funding Information:
Acknowledgment: We are grateful to the U.S.-Israel Binational Science Foundation for a grant in support of this work. A.P. would also like to thank the donors of the Petroleum Research Fund, administeredb y the ACS, for support of this research.

Funding Information:
References and Notes 1. a. Cycloadditions 38. For paper 37 see reference3 a; b. Departmento f Chemistry, Universita di Catania, Catania, Italy. U.C. thanks the NATO Foundation for a travel grant and the M.P.I. for partial financial support. 2. J. Yoshimura Adv. Carb. Chem. 42, 69 (1984); M. Bourgeois Helv. Chim. Acta 56, 2879 (1973); ibid. 58, 363 (1975). 3. a. A. Hassner, K.S.K. Mutthy, A. Padwa, W. H. Bullock and P. D. Stull J. Org. Chem. 53 submitted (1988); b. K.S.K. Murthy and A. Hassner Tetrahedron Lett. 97 (1987). 4. A. Padwa in “1,3-Dipolar Cycloaddition Chemistry”, A. Padwa, Ed.; Wiley-Interscience, New York, Vol. 2, 1984. 5. A. P. Kozikowski Act. Chem. Res. 77 , 410 (1984). 6. T. L. Gilchrist Chem. Sot. Rev. 72, 53 (1983). 7. W. Hobold; U. Prietz and W. Pritzkow J. Prakt. Chem. 377,260 (1969). 8. K. Wieser and A. Berndt Angew. Chem. Int. Ed. Engl. 74, 70 (1975). 9. E. Francotte, R. Merenyi, B. Vandenbulcke-Coyette and H. Viehe Helv. Chim. Acta. 64, 1208 (1981). 10. E. T. Kaiser, J. H. Smith and J. H. Heidema J. Am. Chem. Sot. 94, 9276 (1972). 11. A. P. Kozikowski and Y. Y. Chen J. Org. Chem. 46,5248 (1981); A. P. Kozikowski and P. D. Stein J. Am. Chem. Sot. 707, 2569 (1985). 12. The cycloaddition products were usually obtained as oils and were purified by flash chromatographyo ver silica gel. All new compounds were characterized by ‘Hand tsC-NMR and by high resolution mass spectra. 13. NMR 5b (CDCls, 300 MHz) 6 3.80 (t, lH, J=8.7 Hz), 4.06 (dd, lH, J=l2.2 and 8.2 Hz), 4.22 (p, lH, J=9.4 Hz), 4.43 (t, lH, J=8.7 Hz), 4.58 (t, lH, Jc8.7 Hz), 5.60 (s, 1H) and 7.2-7.5 (m, 5H); NMR 762.86(m, lH), 3.86 (dd, lH, J=ll.2and5.0Hz), 3.95(dd, lH, J=ll.2and5.0 Hz), 4.16 (1, lH, J=9.5 Hz), 4.65 (t, lH, J=9.5 Hz), 4.74 (s, 1H) and 7.2-7.5 (m, 5H). 14. MM2 Calculations were performedo n a Vax 1l /785 using Model 2.92. The relative energy differences of the transition states were estimated by calculating transition state total energy. The program is parameterizedf or transition state carbon (C$,C#,C*) as well as transition state oxygen. Transition-state bond orders of 0.3 were used. 15. NMR 9c 6 4.94 (d, lH, J=l2.0 Hz), 5.02 (d, lH, J~12.0 Hz), 6.10 (s, lH), 7.2-7.6 (m, 5H) and 8.05 (s, 1H ). 16. NMR 11 (Rt=Ph, R2=H,X =0) S 3.15 (m, lH), 3.60 (m, 2H), 3.96 (m, 2H), 4.40 (t, IH, J=9.0 Hz), 4.50 (d, lH, J-6.1 Hz), 5.22 (m, 1H) and 7.2-7.6 (m, 5H). 17. R. Grigg, M. Jordan, A. Taugthongkum,F .W.B. Einstein and T. Jones J. Chem. Sot. Perkin Trans. I 47 (1984). 18. R. Grigg and S. Thianpantangul J. Chem. Sot. Perkin Trans. I 653 (1984) 19. R. Grigg Chem. Sot. Rev. 76, 89 (1987).

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