The reductocondensation of 2,3-dimethoxybenzaldehyde (I) with 2-(3,4-dimethoxyphenyl)-2-hydroxyethylamine (II) by means of NaBH4 in methanol gives N-(2,3-dimethoxybenzyl)-2-(3,4-dimethoxyphenyl)-2-hydroxyethylamine (III), which is cyclized by means of H2SO4 in TFA, followed by an azeotropic distillation with toluene to yield the tetrahydroisoquinoline (IV). Finally, this compound is demethylated by means of refluxing 48 % HBr to provide the target racemic tetrahydroisoquinoline.

Amino alcohol (III) was prepared from veratraldehyde (I) by addition of cyanotrimethylsilane, followed by borane reduction of the resultant cyanohydrin (II). Reductive condensation of amine (III) with 2,3-dimethoxybenzaldehyde (IV) gave the secondary amine (V). This was cyclized to the tetrahydroisoquinoline (VI) under acidic conditions. Resolution of the racemic (VI) by means of dibenzoyltartaric acid furnished the desired (S)-amine, which was further acylated with Ac2O to yield the chiral amide (VII). Demethylation of (VII) with boron tribromide afforded the tetrahydroxy compound (VIII). Finally, acetamide hydrolysis under acidic conditions yielded the title compound.