Hexane → 2-(4-Methylthiophen-2-yl)-1,3,2-dioxaborinane

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To a solution of 3-methylthiophene (10.0 g, 0.1 mol) in 120 ml of anhydrous diethyl ether was added 2.5 M n-BuLi in hexane (40 ml, 0.1 mol) at room temperature. After stirring at room temperature for 30 min, the resulting solution was refluxed for 1 h. The mixture was cooled down to −76° C. and trimethylborate (16.72 ml, 150 mol) was added slowly. The mixture was allowed to warm to room temperature and stirred for 2 h. After quenching with 10% HCl (150 ml), the organic layer was separated and the aqueous layer was extracted with ether (2×). The combined organic layer was dried over MgSO4, filtered and concentrated. The residue was added to 1,3-propanediol (7.3 ml, 0.1 mol) and refluxed for 3 h. The mixture was then placed directly on a silica column and eluted with hexane, then chloroform to give the product, 12.86 g, 71%. 1H NMR (CDCl3-d3, 500 MHz): δ 7.32 ppm (s, 1 H), 7.11 ppm (s, 1 H), 4.14-4.12 ppm (t, 4 H, J=8.6 Hz), 2.40 (s, 3 H), 2.04 ppm (m, 2 H); 13C-NMR (CDCl3, 500 MHz): δ 138.8, 137.8, 127.03 127.02, 62.09, 27.48, 15.23 ppm. EI, MS m/z (%): 182 (100, M+).

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