Tetrabutylammonium Fluoride → 7-hydroxy-6-methoxy-3,4-dihydro-1H-isoquinoline-2-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A 6.0 g portion of 3,4-dihydro-7-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-6-methoxy-2(1H)isoquinolinecarboxylic acid-1,1-dimethylethyl ester is dissolved in 30 mL tetrahydrofuran and cooled to 0° C. To this is added 22.8 mL of a 1.0M solution of tetrabutylammonium fluoride, while stirring. The reaction mixture is brought to room temperature, and stirred for three hours. The reaction is quenched with 10 mL saturated sodium bicarbonate solution and 10 mL water, followed by the addition of 20 mL diethyl ether. After separating the layers, the aqueous phase is extracted with 2×20 mL diethyl ether. The combined organic layers are washed with 20 mL brine, and dried over magnesium sulfate. Following removal of the solvent, the product is purified by silica gel chromatography (eluting with 2:1 hexane/ethyl acetate) to produce 4.15 g of the desired product as a white solid. mp 80°-83° C. MS(Hi res): m/z Calcd for C15H21NO4 279.1470 Found 279.1469 Calcd for C15H21NO4 : C=64.50, H=7.58, N=5.01 Found C=64.47, H=7.61, N=5.19

Provenance & Evidence