Dimethylformamide → 5-(tert-Butyl)-2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)benzaldehyde

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Reaction Conditions

Reaction Steps

To a solution of 101c (50 g, 0.22 mol) in anhydrous THF (750 mL) was added 2.4 M solution of n-butyllithium in hexane (225 mL) at −78° C. under nitrogen atmosphere. The clear amber solution was warmed to −20° C. and stirred for 4 hr. The reaction mixture became red-amber and cloudy. The mixture was re-cooled to −78° C. and stirred rapidly before 72 mL of DMF was added drop wise at such a rate that the temperature was controlled below −60° C. After the addition, the reaction mixture was stirred at −78° C. for 15 min then stirred at −20° C. for 1 hr and room temperature for 1 hr. The reaction mixture was quenched with 200 mL of 0.5 M aqueous KHSO4. More KHSO4 solution was added in until the pH was adjusted to 4-5. The aqueous phase was extracted with EtOAc (3×500 mL) and the combined organic phases was washed with 400 mL of brine and dried over Na2SO4, filtered and concentrated in vacuo to give 101d (35 g, 62%) as a yellow solid which was used in the next step without further purification. LCMS, ESI, m/z 260 (M+1)+.

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