According to one embodiment of the present invention, a tetrahydroisoquinoline compound of the formula (I) can be prepared by condensing 3-hydroxyphenethylamine with a phenylglycidic acid compound of the formula; R-CH wherein Z is an alkyl radical or an alkali metal. and R has the same meaning as defined above The condensation reaction may be accomplished by admixing 3-hydroxy-phenethylamine or it