Trifluoroacetic acid → 1-(2-Methoxyphenyl)-1,2,3,4-tetrahydroisoquinoline

Participants

Reaction Conditions

Reaction Steps

Under an argon atmosphere, a 1.0 M borane-THF complex solution (110 mL) was added to a mixture of (1R,2S)-1-amino-2-indanol (8.17 g) and diethyl ether (200 mL) under stirring at an internal temperature of 5° C. or lower. The mixture was further stirred at room temperature for 1.5 hours. The mixture was cooled to an internal temperature of 4° C. 1-(2-methoxyphenyl)-3,4-dihydroisoquinoline (10 g) was gradually added to the mixture at an internal temperature of 5° C. or lower, followed by stirring at the same temperature for 30 minutes. The mixture was stirred at room temperature for 3 days. Trifluoroacetic acid (61 mL) was added to the reaction mixture to decompose an excess of reagent, further followed by heating under reflux for 3 hours. After cooling, diethyl ether was evaporated under reduced pressure and the mixture was heated under reflux for 10 minutes. The residue was diluted with chloroform and extracted with concentrated aqueous ammonia to be alkaline. The organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (chloroform-EtOH-aqueous ammonia) to obtain 1-(2-methoxyphenyl)-1,2,3,4-tetrahydroisoquinoline (8.23 g).

Provenance & Evidence