Ammonium Chloride → tert-Butyl 3-[2-(tert-butyldiphenylsilanyloxy)ethyl]-6-(3-isobutylcyclobutyl)-4-oxo-5-hexynoate

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Reaction Steps

1-(2,2-Dibromovinyl)-3-isobutylcyclobutane (40 g) and tetrahydrofuran (280 mL) were mixed. To the mixture was added n-butyllithium (2.66 M in hexane) (104 mL) dropwise at −78° C. The mixture was stirred at ice temperature and a solution of tert-butyl 5-(tert-butyldiphenylsilanyloxy)-3-methoxymethylcarbamoylvalerate (54 g) in tetrahydrofuran (100 mL) was added dropwise to the mixture. After stirring at ice temperature for 1 hr, saturated aqueous ammonium chloride (180 mL) and water (100 mL) were added to the reaction mixture. The mixture was extracted with ethyl acetate (600 mL), washed with saturated aqueous ammonium chloride (180 mL and 400 mL) and dried over sodium sulfate. The sodium sulfate was filtered off and the filtrate was concentrated in vacuo. After an addition of silica gel (90 g) and ethyl acetate/hexane=1/20 (600 mL) into the resultant residue, the mixture was stirred at RT for 1 hr. The silica gel was filtered off and the filtrate was concentrated in vacuo to give the title compound (60.09 g) as a crude product.

Provenance & Evidence