Regioselective synthesis of 7-acetyl-11c-methyl-4b,5,7,11c-tetrahydro[1]benzofuro[2′,3′:4,5]thiopyrano[2,3- b ]indoles by sequential Claisen rearrangement of 2-(4′-aryloxybut-2′-ynylthio)-1-acetylindoles
Free accessResearch articleFirst published online May, 2006
Regioselective synthesis of 7-acetyl-11c-methyl-4b,5,7,11c-tetrahydro[1]benzofuro[2′,3′:4,5]thiopyrano[2,3- b ]indoles by sequential Claisen rearrangement of 2-(4′-aryloxybut-2′-ynylthio)-1-acetylindoles
Hitherto unreported indole-annulated pentacyclic heterocycles containing oxygen, nitrogen and sulfur have been synthesised by thermal Claisen rearrangement followed by Lewis acid catalysed Claisen rearrangement. 9-Acetyl-4-aryloxymethyl-2,9-dihydrothiopyrano[2,3-b]indoles are regioselectively synthesised in 80–85 % yield by thermal rearrangement of 2-(4′-aryloxybut-2′-ynylthio)-1-acetylindoles. A second, Lewis acid catalysed, rearrangement gave 7-acetyl-11c-methyl-4b,5,7,11c-tetrahydro[1]benzofuro[2′,3′: 4,5]thiopyrano[2,3-b]indoles in yields of 85–90 %. The thermal Claisen rearrangement in refluxing N,N-diethylaniline for 3 h gave the same products in lower yield (50–54 %).
(a) SendoY., IijimaI., and BanY., Tetrahedron Lett., 1969, 30, 2527; (b) R.J. Sundberg, The Chemistry of Indoles, Academic Press, New York, 1970. pp 438–439; (c) J.E. Saxton, Indoles, Wiley-Interscience, New York, 1983, Part 4; (d) M. Taniguchi, T. Anjiki, M. Nakagawa and T. Hino, Chem. Pharm. Bull., 1984, 32, 2544; (e) J.S. Carle and C. Christophersen, J. Org. Chem., 1980, 45, 1586; (f) Y. Nakashima, Y. Kawashima, F. Amanuma, K. Sota, A. Tanaka and T. Kameyama, Chem. Pharm. Bull., 1984, 32, 4271; (g) T. Ohmoto and K. Koike, Chem. Pharm. Bull., 1984, 32, 170 (h) M. Shimizu, M. Ishikawa, Y. Komoda, T. Nkajima, K. Yamaguchi and N. Yoneda, Chem. Pharm. Bull., 1984, 32, 463; (i) S. Kamijo and Y. Yamamoto, J. Org. Chem., 2003, 68, 4764; (j) Y. Hashimoto, K. Shudo and T. Okamoto, Chem. Pharm. Bull., 1984, 32, 4300; (k) E. Yamanaka, M. One, S. Kasamatsu, N. Aimi and S. Sakai, Chem. Pharm. Bull., 1984, 32, 818.
2.
(a) HaiderN., and SoteroE., Chem. Pharm. Bull., 2002, 50, 1479; (b) C. Guillonneare, A. Pierre, Y. Charton, N. Guilbaud, I. Kraus-Berthier, S. Leonce, A. Michel, I. Bisagni and G. Atassi, J. Med. Chem., 1999, 42, 2191.
3.
(a) SakaiS., AimiN., YamaguchiK., HitotsuyonagiY., WatanabeC., YokoseK., KoyamaY., ShudoK., and ItaiA., Chem. Pharm. Bull., 1984, 32, 354; (b) Y. Endo, K. Shudo, K. Furuhata, H. Ogura, S. Sakai, N. Aimi, Y. Hitotsuyanagi and Y. Koyama, Chem. Pharm. Bull., 1984, 32, 358.
4.
(a) TakadaS., and MakisumiY., Chem. Pharm. Bull., 1984, 32, 872; (b) S. Takada, N. Ishizuka, T. Sasatani, Y. Makisumi, H. Jyoyama, H. Hatakeyama, F. Asanuma and K. Hirose, Chem. Pharm. Bull., 1984, 32, 877.
5.
(a) ThyagarajanB.S., Adv. Heterocyclic Chem., 1967, 8, 143; (b) J.E. Macor, O.D. Langer, J.Z. Gougoutas, M.F. Melley and L.A.M. Cornelius, Tetrahedron Lett., 2000, 41, 3541; (c) S.C. Ghosh and A. De, J. Chem. Soc. Perkin Trans. 1, 1999, 24, 3705; (d) E.W. Baxter, D. Labaree, H.L. Ammon and P.S. Mariano, J. Am. Chem. Soc., 1990, 112, 7682; (e) Y. Tamaru, T. Harada, Y. Toshiro and Z. Yoshida, J. Am. Chem. Soc., 1980, 102, 2392; (f) R.M. Lemieux and A.I. Meyers, J. Am. Chem. Soc., 1998, 120, 5453; (g) D.C. Smith and P.L. Fuchs, J. Org. Chem., 1995, 60, 2692; (h) S. Takano, M. Hirama and K. Ogasawara, Tetrahedron Lett., 1982, 23, 881.
6.
(a) BatesD.K., and JanesM.W., J. Org. Chem., 1978, 43, 3856; (b) P.L. Raymond, Chem. Rev., 1984, 84, 205; (c) N. Katsumasa, B. Hiroshi, M. Keiji and Y. Hisashi, J. Am. Chem. Soc., 1990, 112, 316; (d) F. Zulfiqar and T. Kitazume, Green Chem., 2000, 2, 296.
7.
(a) MajumdarK.C., ChatterjeeP., and SahaS., Tetrahedron Lett., 1998, 39, 7147; (b) K.C. Majumdar, U.K. Kundu and S.K. Ghosh, Org. Lett., 2002, 4, 2629; (c) K.C. Majumdar and U. Das, J. Org. Chem., 1998, 63, 9997.
8.
(a) MajumdarK.C., and ThyagarajanB.S., Int. J. Sulfur Chem.1972, 2A, 93; 1972, 2A, 153; (b) J.B. Hillard, K.V. Reddy, K.C. Majumdar and B.S. Thyagarajan, J. Heterocyclic Chem., 1974, 11, 369.
