The reaction was carried out under a nitrogen atmosphere. TBS- ethylene glycol prepared as per step 1 (85.10g, 0.48 mol) and 2, 6-Lutidine (84.28ml, 0.72 mol) were stirred in n-heptane (425ml) to give a clear solution which was then cooled to -15 to - 25°C. Trifluoromethanesulfonic anhydride (Tf2O) (99.74 ml, 0.590 mol) was added drop-wise over a period of 45 minutes to the n-heptane solution (white precipitate starts to form immediately) while maintaining the reaction at -15 to -25°C. The reaction mixture was kept at temperature between -15 to -25°C for 2 hours. The precipitate generated was filtered off. The filtrate was then evaporated up to ~2 volumes with respect to TBS-ethyiene glycol (~200 ml).
