Acetone → 4-(Bromomethyl)-2,2-dimethyl-1,3-dioxolane

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Into a 500 milliliter round bottom flask equipped with a magnetic stir bar and drying tube, a solution of 28.0 grams (0.181 mole) of 3-bromo-1,2-propanediol in 200 milliliters of acetone was added. Then, 0.5 milliliter of concentrated sulfuric acid was added and the reaction allowed to proceed at room temperature for 24 hours with continuous stirring. The reaction mixture was neutralized with 13.0 grams of K2CO3 for 30 minutes, the solution was filtered and the solvent evaporated in vacuo. The resulting oil was dissolved in 150 milliliter of ether, extracted three times with 150 milliliter portions of water and the organic layer dried over anhydrous sodium sulfate. The filtered ether was evaporated in vacuo and 100 milliliters of hexanes was added, resulting in two layers. The upper layer was decanted and evaporated in vacuo to provide 19.1 grams (53.5%) of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl bromide. The desired analog was then prepared in an analogous manner to that of (±)-3-hexadecylthio-2-methoxy-N,N-dimethyl-N-β-hydroxyethyl-1-propyl ammonium bromide from 2.5 grams (0.013 mole) of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl bromide, 1.3 grams (0.014 mole) of N,N-dimethylaminoethanol, and 15 milliliters of CH3CN. Chromatography with Florisil® (CHCl3 :MeOH 3:1 as eluent) provided 0.860 milligrams (23%) of product as a thick oil. 1H-NMR (CDCl3): delta, 1.25 (s, 3H, CH3), 1.35(s, 3H, CH3), 3.4-3.48[s, 6H, CH2 --N(CH3)2 ], 3.75-4.25(m, 9H, CH, CH2 --O, CH2 --N--CH2 --CH2 --OH). Anal. (C10H22NO3Br) C,H,N.

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