Synthesis and Anti-Monoamine Oxidase Activity of 2-Substituted 4,4-Dimethyl-1,2,3,4-tetrahydroisoquinoline Derivatives

Treatment of N -benzyl-2-methylprop-2-en-1-amine with a mixture of concentrated sulfuric acid and 85% phosphoric acid gave 4,4-dimethyl-1,2,3,4-tetrahydroisoquinoline which was reacted with aromatic carboxylic acid chlorides, and the subsequent reduction afforded 2-arylalkyl tetrahydroisoquinolines. 3-(Tetra­hydroisoquinolin-2-yl)propionic acid derivatives were synthesized by addition of 4,4-dimethyltetrahydro­isoquinoline to the C=C double bond of acrylonitrile and acrylamide. N -Methallyl-3-(benzylamino)propanamide and N -benzyl- N ′-phenylthiourea derivatives were converted into 2-functionalized tetrahydroisoquinolines by the action of a mixture of sulfuric and phosphoric acids.