A flame-dried,500-mL Schlenk flask equipped with a magneticstirring bar, dropping funnel sealed with arubber septum, and an argonballoon is loaded under an atmosphere of argon with18.7 g (90 mmol) of (−)-(S)-ethyl2-(benzyloxy)propanoateand the compound isdissolved in anhydrous diethylether (180 mL). The reaction mixture iscooled to −78°C by meansof a cooling bath (dry ice/ethanol). A 1 M solution of diisobutylaluminumhydride (DIBAH) in hexane (126 mL, 126 mmol) is added very slowly dropwise to thesolution of the ester and stirring is continued for at least 1 hr after thecomplete addition of the DIBAH solution. Upon complete consumption of theester, the crude reaction mixture is poured directly with vigorous stirringinto 360 mL of ice cold 4 N hydrochloricacid. The aqueous phase is extracted with diethylether (4 × 180 mL) and the combined organicextracts are washed with 50 mL of aqueous saturated NaClsolution. After drying over MgSO4, filtration and removal of the solvents under reduced pressure bymeans of a rotary evaporator, 14.4 g (98%) of the crude aldehyde is obtained.
Reference: Organic Syntheses,Coll. Vol. 10, p.66; Vol. 78, p.177