Supporting Information for Synthesis of Zearalenone-16-Β,D-Glucoside
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Supporting Information for Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16- sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation Hannes Mikula*1, Julia Weber1, Dennis Svatunek1, Philipp Skrinjar1, Gerhard Adam2, Rudolf Krska3, Christian Hametner1 and Johannes Fröhlich1 Address: 1Institute of Applied Synthetic Chemistry, Vienna University of Technology (VUT), Getreidemarkt 9/163, A-1060 Vienna, Austria, 2Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Str. 24, 3430 Tulln, Austria and 3Center for Analytical Chemistry, Department for Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Str. 20, 3430 Tulln, Austria * Corresponding author Email: Hannes Mikula* - [email protected] Experimental details (including remarks and general procedures), characterization data, copies of NMR spectra of new compounds, 2D NMR spectra of glucoside 7. Content 1. Experimental ................................................................................................................................................. S3 General remarks .................................................................................................................................................. S3 General procedure A: regioselective acetylation of RAL type compounds ......................................................... S3 4-Acetoxy-2-hydroxybenzoic acid isopropyl ester (10) ...................................................................................... S4 14-O-Acetylzearalenone (14) .............................................................................................................................. S4 General procedure B: regioselective p-methoxybenzylation of RAL type compounds....................................... S4 2-Hydroxy-4-((p-methoxybenzyl)oxy)benzoic acid isopropyl ester (15) ............................................................ S5 14-O-(p-Methoxybenzyl)zearalenone (18) .......................................................................................................... S5 S1 General procedure C: regioselective TIPS-protection of RAL type compounds ................................................. S6 2-Hydroxy-4-(triisopropylsilyloxy)benzoic acid isopropyl ester (21) ................................................................. S6 14-O-(Triisopropylsilyl)zearalenone (22) ........................................................................................................... S6 General procedure D: Königs–Knorr glucosylation ............................................................................................ S7 5-Hydroxy-2-(isopropoxycarbonyl)phenyl-β,D-glucoside (17) ........................................................................... S7 Zearalenone-16-β,D-glucoside (7) ....................................................................................................................... S8 16-O-((2,2,2,-Trichloroethoxy)sulfonyl)-14-O-(triisopropylsilyl)zearalenone (24) ............................................ S8 Zearalenone-16-sulfate, tetrabutylammonium salt (NBu4-8) .............................................................................. S9 2. NMR spectra................................................................................................................................................ S11 Figure S1: COSY spectrum of 7 ....................................................................................................................... S11 Figure S2: HSQC spectrum of 7 ....................................................................................................................... S12 Figure S3: HMBC spectrum of 7 ..................................................................................................................... S12 Figure S4: 1H NMR spectrum of 8 ................................................................................................................... S13 Figure S5: 13C NMR spectrum of 8 .................................................................................................................. S13 Figure S6: 1H NMR spectrum of 10 ................................................................................................................. S14 Figure S7: 13C NMR spectrum of 10 ................................................................................................................ S14 Figure S8: 1H NMR spectrum of 14 ................................................................................................................. S15 Figure S9: 13C NMR spectrum of 14 ................................................................................................................ S15 Figure S10: 1H NMR spectrum of 15 ............................................................................................................... S16 Figure S11: 13C NMR spectrum of 15 .............................................................................................................. S16 Figure S12: 1H NMR spectrum of 17 ............................................................................................................... S17 Figure S13: 13C NMR spectrum of 17 .............................................................................................................. S17 Figure S14: 1H NMR spectrum of 18 ............................................................................................................... S18 Figure S15: 13C NMR spectrum of 18 .............................................................................................................. S18 Figure S16: 1H NMR spectrum of 21 ............................................................................................................... S19 Figure S17: 13C NMR spectrum of 21 .............................................................................................................. S19 Figure S18: 1H NMR spectrum of 22 ............................................................................................................... S20 Figure S19: 13C NMR spectrum of 22 .............................................................................................................. S20 Figure S20: 1H NMR spectrum of 24 ............................................................................................................... S21 Figure S21: 13C NMR spectrum of 24 .............................................................................................................. S21 S2 1. Experimental General remarks All reactions were performed under an argon atmosphere. The progress of reactions was monitored by thin-layer chromatography (TLC) over silica gel 60 F254 (Merck). The chromatograms were visualized by irradiation with ultraviolet light or by heat staining with ceric ammonium molybdate in ethanol/sulfuric acid. LC–ESI–MS/MS was performed on an HCT ion trap mass spectrometer (Bruker, Germany) in full scan mode. Chromatographic separation was done on a 1200 series HPLC system (Agilent Technologies, Germany) using a Luna RP-C18 column (3.0 × 150 mm, 3 µm particle size, Phenomenex, Germany) and application of pure substances was achieved using a TLC–MS interface (Camag, Germany). Preparative column chromatography was performed on silica gel 60 (Merck, 40-63 µm) or RP-C18 silica gel (Merck, 40–63 µm) using a Büchi SepacoreTM Flash System. NMR spectra were recorded on a Bruker DPX-200 MHz or Avance DRX-400 MHz spectrometer. Data were recorded and evaluated using TOPSPIN 1.3 (Bruker Biospin). All chemical shifts are given in ppm relative to tetramethylsilane. The calibration was done using residual solvent signals. Multiplicities are abbreviated as s (singlet), d (doublet), t (triplet), q (quartet), b (broad signal). Zearalenone was obtained from Fermentek (Israel) and all other chemicals were purchased from ABCR (Germany) or Sigma-Aldrich (Austria/Germany). General procedure A: regioselective acetylation of RAL type compounds To a solution of the RAL type compound (1.0 mmol) and DMAP (1.2 mg, 10 µmol) in dry toluene (5 mL) at 0 °C was slowly added a solution of Ac2O (110 mg, 1.1 mmol) in dry toluene (1 mL). The reaction mixture was gradually warmed to room temperature and stirred for further 16 h. The solvent was removed under reduced pressure and the residue was purified by column chromatography (hexanes/EtOAc gradient elution) to yield the desired 4’-O-acetylated product. S3 4-Acetoxy-2-hydroxybenzoic acid isopropyl ester (10) Following general procedure A, 10 was obtained as a white solid (203 mg, 85%); Rf 0.4 1 (hexanes/EtOAc, 9/1); H NMR (200 MHz, CDCl3) δ 11.07 (s, 1H, 2-OH), 7.84 (d, J = 8.8 Hz, 1H, H-6), 6.72 (d, J = 2.3 Hz, 1H, H-3), 6.62 (dd, J = 8.8, 2.3 Hz, 1H, H-5), 5.26 (sept., J = 6.2 Hz, 1H, 13 COOCH), 2.27 (s, 3H, CH3COO), 1.36 (d, J = 6.2 Hz, 6H, (CH3)2CH); C NMR (50 MHz, CDCl3) δ 169.2 (s), 168.5 (s), 162.9 (s), 156.1 (s), 131.0 (d), 112.9 (d), 110.7 (s), 110.4 (d), 69.3 (d), 21.8 (q), + + 21.1 (q); HRMS m/z calcd for C12H14NaO5 [M+Na] 261.0733, found 261.0750. 14-O-Acetylzearalenone (14) Following general procedure A (reduced scale), 14 was obtained starting from ZEN (1, 32 mg, 0.1 1 mmol) as a white solid (27 mg, 75%); Rf 0.4 (hexanes/EtOAc, 2/1); H NMR (200 MHz, CDCl3) δ 11.88 (s, 1H, 16-OH), 7.00 (d, J = 15.6 Hz, 1H, H-12), 6.67-6.62 (m, 2H, H-13, H-15), 5.71 (ddd, J = 15.4, 10.1, 4.3 Hz, 1H, H-11), 5.11-4.93 (m, 1H, H-3), 2.81 (ddd,