[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[O:9][CH:8]([CH2:10]O)[CH2:7][C:6]=2[CH:12]=1.N1C=CC=CC=1.S(Cl)([Cl:21])=O.C(=O)(O)[O-].[Na+]>C1C=CC=CC=1>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[O:9][CH:8]([CH2:10][Cl:21])[CH2:7][C:6]=2[CH:12]=1
To a solution of (5-chloro-2,3-dihydro-1-benzofuran-2-yl)methanol (3 g, 16 mmol) in benzene (50 ml) was added pyridine (1.55 g, 19.6 mmol, 1.2 eq) and thionyl chloride (2.72 g, 23.0 mmol) dropwise with stirring at 0° C. for 7 hours at 80° C. in an oil bath. The reaction mixture was adjusted to ˜pH 8 with aqueous sodium bicarbonate and then extracted with ethyl acetate (3×50 mL). The organic layers were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated under vacuum. The crude material was purified by silica gel chromatography using 3% ethyl acetate in petroleum ether to elute. The product-containing fractions were combined and concentrated under vacuum to afford 5-chloro-2-(chloromethyl)-2,3-dihydro-1-benzofuran as an off-white solid (1.5 g, 46%); 1H NMR (300 MHz, CDCl3): δ 7.06-7.14 (m, 2H), 6.70 (d, J=8.4 Hz, 1H), 4.99-5.10 (m, 1H), 3.64-3.76 (m, 2H), 3.32-3.40 (dd, J=9.3 Hz, 16.2 Hz, 1H), 3.09-3.17 (dd, J=6.6 Hz, 16.2 Hz. 1H).
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