Allyl bromide → (+/-)-(6-Allyl-5-chloro-7-hydroxy-2,3-dihydro-1-benzofuran-2-yl)methyl 4-methylbenzenesulfonate

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Treatment of (±)-(5-chloro-7-methoxy-2,3-dihydro-1-benzofuran-2-yl)methyl 4-methylbenzenesulfonate (22.1 g, 0.06 mol) with hydrogen bromide (30 wt. % in acetic acid, 400 mL) followed by potassium carbonate (4.15 g, 0.03 mol) provided (±)-(5-chloro-7-hydroxy-2,3-dihydro-1-benzofuran-2-yl)methyl 4-methylbenzenesulfonate as a brown oil. Treatment of the phenyl with sodium hydride (3.2 g, 0.053 mol) and allyl bromide (6.4 g, 0.053 mol) generally according to the procedure described for Intermediate 37 afforded (±)-[7-(allyloxy)-5-chloro-2,3-dihydro-1-benzofuran-2-yl]methyl 4-methylbenzenesulfonate. Treatment of the allyl ether in refluxing mesitylene (250 mL) generally according to the procedure described for Intermediate 1 afforded 4.5 g (19%) of (±)-(6-allyl-5-chloro-7-hydroxy-2,3-dihydro-1-benzofuran-2-yl)methyl 4-methylbenzenesulfonate as a pale yellow solid. mp 128-131° C.; Anal. calcd. for C19H19ClO5S: C, 57.79; H, 4.85. Found: C, 58.28; H, 4.68.

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