2,2-Dimethyl-3-(tetrahydro-pyran-2-yloxy)-propan-1-ol → 2,2-Dimethyl-3-((tetrahydro-2H-pyran-2-yl)oxy)propanal

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Reaction Steps

To a stirred solution of 2,2-dimethyl-3-(tetrahydro-2H-pyran-2-yloxy)propan-1-ol (20 g, 106 mmol) an TEA (44.4 mL, 319 mmol) in dry dichloromethane (300 mL) cooled in an ice bath to 0° C.±5° C. was added a solution of sulfur trioxide pyridine complex (50.7 g, 319 mmol) in anhydrous DMSO (300 mL) in one portion. There was an exotherm to 27° C. The bath was removed and the mixture allowed to stir for 20 minutes at room temperature after which time conversion was complete by TLC. The reaction was quenched with 225 mL of saturated NaHCO3, concentrated on the rotovap to remove dichloromethane and extracted with 3×200 mL of ethyl acetate. The combined extracts were washed once with 250 mL of 10% citric acid, dried over MgSO4 and concentrated. Drying under vacuum gave 2,2-dimethyl-3-(tetrahydro-2H-pyran-2-yloxy)propanal as an oil. Contains ˜40% DMSO by NMR: 1H NMR (400 MHz, CDCl3) δ 9.6 (s, 1H), 4.6 (m, 1H), 3.8 (d, 1H), 3.5 (m, 1H), 3.38 (d, 1H), 1.8-1.4 (min, 6H), 1.06 (s, 3H), 1.04 (s, 3H).

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