Dimethyl Sulfoxide (Alfa Aesar)
Oxalyl Chloride (Aldrich, freshly distilled)
Dichloromethane (Dried over Calcium Hydride)
Triethylamine (Distilled and stored over KOH)

Dimethyl sulfoxide (510 µL, 7.21 mmol, 4 equiv.) was added dropwise to a stirred solution of oxalyl chloride (310 µL, 3.60 mmol, 2 equiv) in dichloromethane (6.7 mL) at -78 °C. After stirring for 30 min, a solution of (R)-3-(benzyloxy)-2-methylpropan-1-ol (325 mg, 1.80 mmol, 1 equiv.) in dichloromethane (1.8 mL) was added via cannula. Stirring was continued for a further 1 h at -78 °C, then triethylamine (1.26 mL, 9.01 mmol, 5 equiv.) was added dropwise and the reaction mixture was allowed to warm to rt (ca. 1 h). 1.0 M aq. ammonium chloride (14 mL) was then added and the phases were separated. The organic phase was washed with 1.0 M aq. ammonium chloride (5 × 10 mL) and sat. brine (15 mL), then dried over sodium sulfate, filtered and concentrated in vacuo to afford (S)-3-(benzyloxy)-2-methylpropanal (314 mg, 98%) as a yellow oil.

1H (400 MHz, Chloroform) 1.15 (3H, d, J 7.0, CH3), 2.63 - 2.72 (1H, m), 3.66 (1H, dd, J 9.5, 5.5), 3.70 (1H, dd, J 9.5, 6.5), 4.54 (2H, s), 7.28-7.39 (5H, m), 9.74 (1H, d, J 1.5) 13C (101 MHz, Chloroform) 10.7, 46.8, 70.0, 73.3, 127.6, 127.7, 128.4, 137.8, 203.9.

Zampella, A.; Sorgente, M.; D'Auria, M. V., Tetrahedron: Asymmetry, 2002, 13, 681 - 685 doi:10.1016/S0957-4166(02)00178-7

Harried, S. S.; Lee, C. P.; Yang, G.;Lee, T. I. H.; Myles, D. C., J. Org. Chem., 2003, 68, 6646 - 6660 doi:10.1021/jo034521r
Omura, K. ; Sharma, A. K.; Swern, D., J. Org. Chem., 1976, 41, 975 - 962 doi:10.1021/jo00868a012