Synlett 2015; 26(16): 2285-2287
DOI: 10.1055/s-0035-1560053
letter
© Georg Thieme Verlag Stuttgart · New York

Synthesis of 3-Aryl-2-nitroindoles by Palladium-Catalyzed CH-Activation Reactions

Anton Ivanov
a   Institut für Chemie, Universität Rostock, Albert Einstein Str. 3a, 18059 Rostock, Germany   Email: peter.langer@uni-rostock.de   Email: iva108@googlemail.com
,
Viktor O. Iaroshenko*
a   Institut für Chemie, Universität Rostock, Albert Einstein Str. 3a, 18059 Rostock, Germany   Email: peter.langer@uni-rostock.de   Email: iva108@googlemail.com
b   National Taras Shevchenko University, Department of Chemistry, 62 Volodymyrska st., Kyiv-33, 01033, Ukraine
,
Alexander Villinger
a   Institut für Chemie, Universität Rostock, Albert Einstein Str. 3a, 18059 Rostock, Germany   Email: peter.langer@uni-rostock.de   Email: iva108@googlemail.com
,
Peter Langer*
a   Institut für Chemie, Universität Rostock, Albert Einstein Str. 3a, 18059 Rostock, Germany   Email: peter.langer@uni-rostock.de   Email: iva108@googlemail.com
c   Leibniz-Institut für Katalyse an der Universität Rostock e.V., Albert Einstein Str. 29a, 18059 Rostock, Germany
› Author Affiliations
Further Information

Publication History

Received: 04 June 2015

Accepted after revision: 02 July 2015

Publication Date:
17 August 2015 (online)


Abstract

3-Aryl-2-nitroindoles were prepared via CH-activation reactions of N-methyl-2-nitroindole.

Supporting Information

 
  • References and Notes

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  • 13 General Procedure for the Synthesis of 2a–mIn a Schlenk flask 1 (100 mg, 0.57 mmol), appropriate aryl bromide (2.28 mmol, 4 equiv), Pd(OAc)2 (0.057 mmol, 10 mol%), K2CO3 (0.8 mmol, 1.4 equiv), and DMF (5 mL) were added under argon atmosphere and stirred at 150 °C overnight. The reaction mixture was then evaporated to dryness, and the product was isolated by column chromatography (silica gel, hexane–EtOAc) or via semipreparative HPLC (MeOH–H2O).
  • 14 1-Methyl-2-nitro-3-phenylindole (2a)Starting with 1 (100 mg, 0.57 mmol), bromobenzene (358 mg, 0.24 ml, 2.28 mmol), Pd(OAc)2 (12.8 mg, 0.057 mmol, 10 mol%), K2CO3 (111 mg, 0.8 mmol), and DMF (5 mL), 2a was isolated as a yellow solid (72 mg, 52%), mp 118–119 °C. 1H NMR (300 MHz, DMSO-d 6): δ = 4.09 (s, 3 H, CH3), 7.28 (t, 3 J H–H = 7.52 Hz, 1 H, ArH), 7.49–7.61 (m, 7 H, ArH), 7.78 (d, 3 J H–H = 8.5 Hz, 1 H, ArH). 13C NMR (75 MHz, DMSO-d 6): δ = 32.6 (CH3), 111.8 (CH), 118.6 (C), 121.8 (C), 122.4 (CH), 124.0 (C), 127.8 (CH), 127.9 (CH), 128.42 (CH), 129.9 (CH), 131.3 (C), 136.1 (C), 138.1 (C). IR (KBr): 1612 (w), 1548 (w), 1501 (m), 1458 (s), 1365 (s), 1303 (s), 1246 (s), 1208 (m), 1178 (m), 1157 (m), 1130 (m), 1113 (m), 1091 (m), 1069 (m), 1028 (m), 978 (w), 923 (m), 897 (m), 858 (w), 779 (m), 769 (m), 753 (s), 740 (s), 699 (s), 642 (m), 604 (s), 550 (m) cm–1. MS (EI, 70 eV): m/z (%) = 253 (18), 252 (M+, 100), 235 (15), 223 (10), 222 (20), 221 (10), 207 (25), 206 (12), 205 (21), 204 (20), 195 (12), 194 (15), 192 (10), 191 (24), 190 (36), 181 (21), 178 (12), 166 (10), 165 (49), 164 (19), 163 (20), 152 (15), 151 (10). HRMS (EI, 70 eV): m/z calcd for C15H12O2N2 [M+]: 252.08933; found: 252.08938.