Acetyl chloride → 5-{2-[2-(3-Chloro-phenyl)-2-hydroxy-ethylamino]-propyl}-benzo[1,3]dioxole-2,2-dicarboxylic acid bis-trimethylsilanylmethyl ester

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Reaction Steps

Acetyl chloride (0.59 g, 7.5 mmol) was added to trimethylsilylmethanol (4.03 g, 37.5 mmol) with stirring at room temperature. After 0.5 h, 5-{2-[2-(3-chloro-phenyl)-2-hydroxy-ethylamino]-propyl}-benzo[1,3]dioxole-2,2-dicarboxylic acid (1.05 g, 2.5 mmol) was added in portions. The resulting solution was stirred for 3 days, and then treated with 50 ml of 50% sodium bicarbonate solution, followed by extraction with ethyl acetate (50 ml). The organic extract was dried over anhydrous sodium sulfate, filtered, and evaporated. The residue was passed through a pad of silica gel, eluting with hexanes, and ether-hexanes/1:1 until no more trimethylsilylmethanol could be detected. The filter pad was then eluted with ethyl acetate, and the solvent was evaporated to give 1.14 g of the desired product as a colorless gum. Conversion to the HCl salt yielded 1.16 g of white foam; 1H NMR (CDCl3) δ 0.06 (s, 18H), 1.33 (d, J=6.5 Hz, 3H), 2.80 (m, 1H), 3.15 (m, 1H), 3.20 (m, 1H), 3.48 (m, 2H), 4.014 (s, 2H), 4.015 (s, 2H), 5.45 (bd, J=9.7 Hz, 1H), 5.60 (bs, 1H), 6.80 (m, 3H), 7.25 (m, 2H), 7.45 (s, 1H), 8.70 (bs, 1H), 10.10 (bs, 1H); IR (KBr): 1763 cm-1 (C=O); MS (ES) m/z 594 (MH+); [α]D25 -23° (c, 1.0, CHCl3). Anal. Calcd. for C28H40ClNO7Si2 ·HCl: C, 53.32; H, 6.39; N, 2.22; Cl, 11.24; Si, 8.91. Found: C, 52.65; H, 6.70; N, 2.11; Cl, 11.47; Si, 9.00.

Provenance & Evidence