Mild Methodology for [4+1] Pyrroline Annulation. Second Generation Synthesis of Pyrrolizidine Alkaloids

References

• Fellow of the Alfred P. Sloan Foundation, 1981–85; Recipient of the National Institutes of Health Research Career Development Award, 1984–1989 (AI-00564)
   Google Scholar
• Hudlicky , T. , Frazier , J. O. and Kwart , L. D. 1985 . Tetrahedron Lett. , : 3523 Pearson, W. H. Tetrahedron Lett., 1985, 3527
   Google Scholar
• Hudlicky , T. , Frazier , J. O. , Seoane , G. , Tiedje , M. , Seoane , A. , Kwart , L. D. and Beal , C. J. 1986 . Am. Chem. Soc. , 108 : 3755 See this paper for detailed discussion of reaction pathways and product distribution
   Google Scholar
• Schneider , P. 1967 . J. Org. Chem. , 32 : 2628
   Google Scholar
• Olah , G. A. and Narang , S. C. 1982 . Tetrahedron , 38 : 2225
   Web of Science ®Google Scholar
• Miller , R. D. and McKean , D. R. 1981 . J. Org. Chem. , 46 : 2412
   Web of Science ®Google Scholar
• Hudlicky , T. , Radesca , L. , Luna , H. C. and Anderson , F. A. III . 1986 . J. Org. Chem. , 51 : 4746 Hudlicky, T.; Sinai-Zingde, G.; Fleming, A.; Natchus, M. G., Tetrahedron Lett., 1987, 28, 167
   Web of Science ®Google Scholar
• Iwashita , T. , Kusumi , T. and Kakisawa , H. 1976 . Chem. Lett. , : 3799 The use of NaI in this rearrangment is documented (see ref. 4). The intramolecular alkylation of the saturated and reduced analogue of 3 has been reported. In that case the trimethylsilyl amine did not spontaneously cyclize onto a primary iodide and required further reaction
   Google Scholar
• The allylic iodide in 3 cyclizes spontaneously due to its increased reactivity over the saturated primary halide (see ref. 8). Mediation of these events by fluoride ion is not necessary. The iodide ion must participate in the desilylation of nitrogen either before or after the cyclization of 3
   Google Scholar
• Short , R. P. , Revol , J. M. , Ranu , B. C. and Hudlicky , T. 1983 . J. Org. Chem. , 48 : 4453 The use of this strategy of peripheral stereochemical control was first reported in connection with the synthesis of isocomenes and isocomenic acids
   Google Scholar
• The reduction of ester 4 did not proceed cleanly. Under the conditions reported in the literature, the yield of supinidine never exceeded 20% (evaluated from crude 1H-NMR spectra)
   Google Scholar
• Kametani , T. , Yukawa , H. and Honda , T. 1986 . J. Chem. Soc. Chem. Commun. , : 651 For compilation of recent syntheses of pyrrolizidine alkaloids see for example: Blum, Z.; Ekstrom, M.; Wistrand, L. G. Acta Chem. Scand., 1984 B 38, 297; Ishibashi, H.; Ozeki, H.; Ikada, M., J. Chem. Soc. Chem. Commun., 1986, 654; reference 3 above
   Google Scholar
• Danishefsky , S. , McKee , R. and Singh , R. K. 1977 . J. Am. Chem. Soc. , 99 : 4783 There are over 25 literature references to the synthesis of title alkaloids. Very few contain complete spectral data for the precursory esters or the title compounds. Notable exceptions are the following references in which authors also acknowledge the difficulties associated with the provision of pure samples of 5, 7, and 9: Tatsuta, K.; Takahashi, H.; Amemiya, Y.; Kinoshita, M., J. Am. Chem. Soc., 1983, 105, 4096; Pinnick, H. W.; Chang, Y. H., J. Org. Chem., 1978, 43, 4662; Mohanraj, S.; Herz, W., J. Nat. Prod., 1982, 45, 328
   Google Scholar