Synthesis of 3-methyl-1,2,3,4-tetrahydroisoquinoline derivatives

Abstract

Using the structure of ancistrotectorine as the lead molecule, a design and synthetic strategy for the preparation of 3-methyl-1,2,3,4-tetrahydro-isoquinoline and derivatives have been studied. The condensation of 3,5-dimethoxy benzaldehyde with nitroethane afforded the nitrostyrene, which was subsequently reduced to obtain the amine and follow by schiff base formation which was reduced to afford the N-benzyl phenylethylamine. The N-benzyl phenylethylamine was treated with paraformaldehyde or butyl glyoxalate, via the N,O-acetal intermediate and was further intramolecular cyclized with acidic catalysis to afford the 1,2,3,4-tetrahydroisoquinolines. Compounds with variations of the substituents on positions 1 and 2 of the tetrahydroisoquinoline were also prepared. The structures of the compounds synthesized were determined by the spectroscopic techniques.