Synlett 2017; 28(04): 467-470
DOI: 10.1055/s-0036-1588917
letter
© Georg Thieme Verlag Stuttgart · New York

An Unprecedented Octahydro-3H-oxeto[2,3,4-ij]isochromene Ring System Formed by a Trichloromethyl-Anion-Induced Reaction Cascade

Witali Schmidt
a   Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany   eMail: stefan.schulz@tu-bs.de
,
Peter G. Jones
b   Institute of Inorganic and Analytical Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany
,
Jennifer Herrmann
c   Department Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
,
Rolf Müller
c   Department Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
,
Stefan Schulz*
a   Institute of Organic Chemistry, Technische Universität Braunschweig, Hagenring 30, 38106 Braunschweig, Germany   eMail: stefan.schulz@tu-bs.de
› Institutsangaben
Weitere Informationen

Publikationsverlauf

Received: 19. September 2016

Accepted after revision: 02. November 2016

Publikationsdatum:
18. November 2016 (online)


Abstract

Sigillin A is a unique polychlorinated, insect repellent natural product, isolated recently from springtails. During the exploitation of an access to such compounds using a trichloromethyl-anion-induced epoxide opening as key step a new synthetic compound was found. A five-step cascade reaction leads to an oxeto[2,3,4-ij]isochromene compound, including a rare oxetane acetal as well as an trichloroenol ether group. Biological data on the antibacterial properties of this compound and sigillin A are reported as well.

Supporting Information

 
  • References and Notes

  • 1 Schmidt W, Schulze TM, Brasse G, Nagrodzka E, Maczka M, Zettel J, Jones PG, Grunenberg J, Hilker M, Trauer-Kizilelma U. Angew. Chem. Int. Ed. 2015; 54: 7698
  • 2 Zettel J, Zettel U. Mitt. Naturforsch. Ges. Bern 2008; 65: 79
  • 3 Crandall JK, Rambo E. Tetrahedron 2002; 58: 7027
  • 4 Henegar KE, Lira R. J. Org. Chem. 2012; 77: 2999
  • 5 Imai T, Nishida S, Tsuji T. J. Chem. Soc., Chem. Commun. 1994; 2353
  • 6 Fürst A, Plattner PA. Helv. Chim. Acta 1949; 32: 275
  • 7 Synthesis of 10 Abs. CHCl3 (0.478 g, 0.323 mL, 4.00 mmol) was added to abs. THF (15 mL), cooled to –98 °C and finally n-BuLi (2.50 mL, 1.6 M in hexane, 4.00 mmol) was added. After stirring for 15 min, a solution of epoxide 8 (24 mg, 0.08 mmol) in abs. THF (1 mL) was slowly added. The reaction mixture was allowed to warm up to –60 °C during 3 h. After hydrolysis with sat. aq NH4Cl, the phases were separated and the water phase was extracted three times with CH2Cl2. The combined organic phases were dried with MgSO4, filtered, and the solvent was evaporated. The crude product was purified by flash chromatography on silica (pentane–Et2O, 10:1). The product was isolated as colorless crystals (13 mg, 0.024 mmol, 30%). Rf = 0.61 (pentane–Et2O, 2:1) 1H NMR (400 MHz, CDCl3, TMS): δ = 5.00 (d, 1 H, H-7a, 3 J H,H = 3.8 Hz), 4.95 (dd, 1 H, H-3, 3 J H,H = 8.5, 7.2 Hz), 4.76 (ddd, 1 H, H-7, 3 J H,H = 12.8, 4.4, 3.8 Hz), 2.68 (dddd, 1 H, H-4a, 3 J H,H = 13.4, 11.1, 7.8, 5.8 Hz), 2.17–2.08 (m, 1 H, H-6), 2.14–2.06 (m, 1 H, H-4), 2.07–1.99 (m, 1 H, H-5), 1.83 (ddd, 1 H, H-4, 2 J H,H = 13.6, 13.0, 8.6 Hz), 1.71–1.64 (m, 1 H, H-5), 1.69–1.60 (m, 1 H, H-6), 1.46 (s, 3 H, CH3). 13C NMR (100 MHz, CDCl3, TMS): δ = 139.99 (COCl), 109.36 (CCl2), 108.71 (C-1a), 100.44 (1a-CCl3), 99.78 (3-CCl3), 86.47 (C-7a), 84.35 (C-3), 82.14 (C-7), 44.73 (C-1a), 33.64 (C-4a), 26.36 (C-4), 22.88 (C-6), 21.15 (C-5), 10.20 (CH3). HRMS (ESI+): m/z calcd 566.7959 [M + Na]+; found: 566.7960.
  • 8 CCDC 1504299 (8), 1504300 (9), 1504301 (10), and 1504302 (11) contain the supplementary crystallographic data for this paper. The data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/getstructures.
  • 9 Köbrich G. Angew. Chem., Int. Ed. Engl. 1972; 11: 473
    • 10a Griesbeck AG, Stadtmueller S. J. Am. Chem. Soc. 1990; 112: 1281
    • 10b Adam W, Kliem U, Peters EM, Peters K, von Schnering HG. J. Prakt. Chem. 1988; 330: 391
    • 11a Karakhanov EA, Lysenko SV, Kovaleva NF, Brezhnev LY, Glukhovtsev VG, Karakhanov RA. Vestn. Mosk. Univ., Ser. 2: Khim. 1982; 23: 159
    • 11b Sugimura H, Osumi K. Tetrahedron Lett. 1989; 30: 1571