1,3-Bis(trimethylsilyloxy)propane

Typical Procedure: To a solution of carbonyl compound (2 mmol), 1,3-bis(trimethylsilyloxy)propane (2.6–10 mmol) in anhydrous CH2Cl2 (10 mL), NBS (0.06–0.14 mmol) is added, and the resulting solution is stirred at room temperature. After completion of the reaction (TLC or GC), a cold aq. solution of NaOH (5%, 25 mL) is added and the mixture is extracted with CH2Cl2 (3 × 15 mL). The organic extracts are washed successively with NaOH (5%, 15 mL), water (4 × 15 mL) and dried over anhydrous Na2SO4. Evaporation of the solvent under reduced pressure gives almost pure products. Further purification is carried out by vacuum distillation, re-crystallization in appropriate solvent or flash chromatography using appropriate eluent to afford pure acetals.