Br[C:2]1[CH:8]=[C:7]([N+:9]([O-:11])=[O:10])[CH:6]=[CH:5][C:3]=1[NH2:4].[C:12]([CH:14]1[CH2:16][CH2:15]1)#[CH:13]>C(N(CC)CC)C.[Cu]I.Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1>[CH:14]1([C:12]#[C:13][C:2]2[CH:8]=[C:7]([N+:9]([O-:11])=[O:10])[CH:6]=[CH:5][C:3]=2[NH2:4])[CH2:16][CH2:15]1To a deoxygenated solution of 2-bromo-4-nitroaniline (2.17 g, 0.01 mmol), ethynylcyclopropane (1 g, 15 mmol) and CuI (10 mg, 0.05 mmol) in triethylamine (20 mL) was added Pd(PPh3)2Cl2 (210 mg, 0.3 mmol) under N2. The mixture was heated at 70° C. and stirred for 24 hours. The solid was filtered off and washed with EtOAc (50 mL×3). The filtrate was evaporated under reduced pressure, and the residue was purified by column chromatography on silica gel (petroleum ether/ethyl acetate=10/1) to give 2-(cyclopropylethynyl)-4-nitroaniline (470 mg, 23%). 1H NMR (300 MHz, CDCl3) δ 8.14 (d, J=2.7 Hz, 1H), 7.97 (dd, J=2.7, 9.0 Hz, 1H), 6.63 (d, J=9.0 Hz, 1H), 4.81 (brs, 2H), 1.55-1.46 (m, 1H), 0.98-0.90 (m, 2H), 0.89-0.84 (m, 2H).
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