Tetrahydrofuran → (S)-5-(2-Hydroxyethyl)-2,2-dimethyl-1,3-dioxolan-4-one

Beteiligte Stoffe

Reaktionsschritte

In a 500 mL flame-dried round bottom flask fitted with a septum and under argon was placed 11.0 g (63.2 mmol) of the dioxolanate of (S)-malic acid (prepared by reaction of commercially available (S)-malic acid with excess dimethoxypropane and p-toluenesulfonic acid as a catalyst) dissolved in 200 mL anhydrous tetrahydrofuran. The reaction was cooled (-20° C. to -30° C.) and 70 mL of 1 M borane-tetrahydrofuran complex was added dropwise over 2 h. Following addition the reaction vessel was placed in a refrigerator at 4° C. for 11 h, warmed to room temperature, stirred at room temperature for 9 h and chromatographed (silica gel) using acetone as eluant. Following evaporation under reduced pressure, the residue was chromatographed as before to generate 9.1 g (90%) of the alcohol as a colorless unstable liquid which was dried under reduced pressure and utilized as such in the next reaction: IR (neat, cm-1) 3480 (br), 2994, 2940, 2888, 1791, 1220; 1H NMR (CDCl3) δ 4.58 (dd, J=5.1, 7.0 Hz, 1H), 3.91-3.79 (m, 2H), 2.28-2.13 (m, 1H), 2.13-1.97 (m, 1H), 1.64 (s, 3H), 1.57 (s, 3H).

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