Arkivoc 2018, iv, 149-157
Miles, K. C. et al.
Experimental Section
General. Melting points were determined via the use of open capillaries with an Electrothermal melting point
apparatus. Elemental analyses was performed by Midwest Microlab, Indianapolis, IN and High Resolution
Mass Spectrometry was performed using a Thermo Scientific LTQ-FT instrument by University of Cincinnati
Mass Spectroscopy Facility, Cincinnati, OH. Elemental analysis results are within +0.4% of the theoretical
1
values. The H and 13C NMR data were obtained on a Bruker Avance 300 MHz NMR in CDCl3 solution unless
otherwise indicated. Chemical shifts for proton NMR are reported in δ (ppm) downfield from tetramethyl-
silane as an internal standard and 13C NMR shifts were calibrated on the CDCl3 resonance at 77.23 ppm or on
the DMSO-d6 resonance of 39.50 ppm. GC/MS measurements were performed using a Hewlett-Packard 6890
Series GC with auto injection and mass fragments are reported as mass per charge, m/z. The GC was coupled
with a mass spectrometer with Hewlett-Packard 5973 mass selective detector/quadrupole system. Flash
were performed on silica gel with indicated solvent systems. All microwave reactions were performed in a
CEM Discover 300 Watt system at the specified temperatures and times.
General procedure, exemplified with the synthesis of 4-[1-(phenylsulfonyl)-1H-pyrrol-2-yl]butan-2-one (2b)
To a 10 mL microwave vial charged with THF (2.5 mL) was added pyrrole or indole (1.2 mmol), MVK (2 equiv)
and bismuth triflate (10 mol %). The reaction vessel was sealed and heated under microwave irradiation in a
CEM Discover 300 Watt microwave reactor for 5 min at 170 °C with a pre-stirring of 15 sec. The crude mixture
was purified by column chromatography on silica gel (hexane:DCM 70:30) to afford pure 4-[(1-
o
1
phenylsulfonyl)pyrrol-2-yl]butan-2-one (2b). Mp 85–87 C; GC/MS m/z 277 (M+), 234 (100%), 141, 77; H
NMR δ: 7.76 (dt, J 7.4 Hz, 1.5 Hz, 2H), 7.60 (tt, J 7.4 Hz, 1.5 Hz, 1H), 7.50 (tt, J 7.4, J 1.5 Hz, 2H), 7.29 (q, J 1.6 Hz,
1H), 6.20 (t, J 3.3 Hz, 1H), 5.98 (m, 1H), 2.93 (t, J 7.4, 2H), 2.75 (t, J 7.4, 2H), 2.11 (s, 3H); 13C NMR (CDCl3, 300
MHz) δ: 207.4, 139.3, 134.3, 134.0, 129.6, 126.8, 122.9, 113.0, 111.8, 43.3, 30.0, 21.7. Anal. Calcd for
C14H15NO3S: C, 60.63; H, 5.45; N, 5.05. Found: C, 60.61; H, 5.33; N, 5.02 %.
4-(1-Benzoyl-1H-pyrrol-2-yl)butan-2-one (2a). GC/MS m/z 241 (M+), 136, 119, 105 (100%), 77; 1H NMR δ: 7.65
(dt, J 7.3, 1.6 Hz, 2H), 7.53 (tt, J 7.3 Hz, 1.5 Hz, 1H), 7.42 (tt, J 7.3, J 1.5 Hz, 2H), 6.71 (t, J 2.5 Hz, 1H), 6.04
13
(m,2H), 3.17 (t, J 7.4 Hz, 2H), 2.78 (t, J 7.4, 2H), 2.10 (s, 3H); C NMR δ: 208.2, 169.6, 136.1, 134.5, 132.5,
129.9, 128.6, 123.7, 113.0, 110.8, 43.7, 30.0, 23.2. HRMS: m/z calcd for [M+H]+ C15H16NO2 242.11756, found
242.11761.
o
4-[1-(4-Nitrophenylsulfonyl)-1H-pyrrol-2-yl]butan-2-one (2c). Mp 117–119 C; GC/MS: m/z 322 (M+), 279,
186, 136 (100%), 94, 1H NMR (DMSO-d6) δ: 8.43 (dt J 8.8, 2.0 Hz, 2H) , 8.10 (dt J 8.8, 2.0 Hz, 2H), 7.40 (m, 1H),
6.33 (t, J 3.3 Hz, 1H), 6.12 (m, 1H), 2.82 (t, J 6.5 Hz, 2H), 2.77 (t, J 6.5 Hz, 2H), 2.09 (s, 3H), 13C NMR (DMSO-d6)
δ: 206.8, 150.6, 143.1, 134.4, 128.2, 125.2, 122.7, 113.0, 112.8, 41.3, 29.6, 20.9. Anal. Calcd for C14H14N2O5S: C,
52.17; H, 4.38; N, 8.69. Found: C, 52.05; H, 4.46; N, 8.53 %.
4-[5-Benzyl-1-(phenylsulfonyl)-1H-pyrrol-2-yl]butan-2-one (2d). GC/MS: m/z 367 (M+), 310, 226 (100%), 168,
91; 1H NMR δ: 7.39 – 6.84 (m, 10 H), 5.68 (d, J 3.5 Hz, 1H), 5.44 (d, J 3.5 Hz, 1H), 3.90 (s, 2H), 2.84 (t, J 7.4 Hz,
2H), 2.57 (t, J 7.4 Hz, 2H), 1.90 (s, 3H); 13C NMR δ: 207.8, 140.3, 138.9, 136.9, 136.6, 133.6, 129.5, 129.4, 128.5,
126.6, 126.2, 113.7, 112.0, 43.9, 35.4, 30.0, 23.5. HRMS: m/z calcd for [M+Na]+ C21H21NO3SNa 390.1141, found
390.1140.
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