An efficient two step synthesis of pyranoquinoline alkaloids is described. Direct treatment of isoprene with 4-hydroxyquinolin-2(1H)-one in the presence of polyphosphoric acid furnished dihydroflindersine in good yield, and which on dehydrogenation led to a new synthesis of flindersine. Khaplofoline, a linear pyranoquinoline alkaloid, was obtained as a minor product. The syntheses of derivatives are also documented.
(a) MathesH., SchreiberE., Ber dert pharm ges, 1914, 24, 385; (b) R.F.C. Brown, J.J. Hobbs, G.K. Hughes and E. Ritchie, Aust. J. Chem., 1954, 7, 348; (c) A.V. Robertson, Aust. J. Chem., 1963, 16, 451; (d) D. Lavie, N. Danieli, R. Weitman and E. Glotter, Tetrahedron, 1968, 24, 3011; (e) M.A. Munoz, M.R. Torres, B.K. Cassels, J. Nat. Prod., 1982, 45, 367; (f) A. Ulubelen, Phytochemistry, 1984, 23, 2123; (g) S. Ahmad, J. Nat. Prod., 1984, 47, 391, (h) S. Mitaku, A.L. Skaltsounis, F. Tillequin and M. Koch, J. Nat. Prod., 1985, 48, 772.
2.
(a) ChouF.Y., HostettmannK., KuboI., NakanishiK., and TaniguchiM., Heterocycles, 1977, 7, 969; (b) K. Hostettmann, M.J. Pettei, I. Kubo and K. Nakanishi, Helv. Chim. Acta 1977, 60, 670; (c) L. Jurd, R.Y. Wong, Aust. J. Chem. 1981, 34, 1625; (d) C. Moulis, K.R. Wira sutisna, J. Gleye, P. Loiseau, E. Stanislas and C. Moretti, Phytochemistry, 1983, 22, 2095.
3.
(a) FakhrutdinovaI.M., SidyakinG.P., and YunusovS.Yu., Uzbeksk. Khim. Zhur., 1963, 7, 41; (b) V.I. Akhmedzhanova, I.A. Bessonova and S. Yu. Yunusov, Khim. Prir. Soedin. 1974, 109; (c) V.I. Akhmedzhariova, I.A. Bessonova and S. Yu. Yunusov, Chemistry of Natural compounds, 1975, 10, 121; (d) M.S. Hifnawy, J. Vaquette, T. Sevenet, J.L. Povsset and A. Cave, Planta Med., 1976, 29, 346; (e) C.L. Cantrell, K.K. Schrader, L.K, Mamonov, G.T. Sitpaeva, T.S. Kustova, C. Dunbar and D.E. Wedge, J. Agric. Food Chem., 2005, 53, 7741.
4.
JansenO., FrederichM., TitsM., AngenotL., ChariotA., OllivierE., BalansardG., and AkhmedjanovaV., Symposium on Plants in Health and Culture held on February 16-17, 2004, Leiden University Leiden, Netherland.
5.
RahmaniM., LingC.Y., MeonS., IsmailH.B.M., and SukariM.A., Pharmaceut. Biol. (Form. Intl. J. Pharmacognosy), 2004, 42, 430.
