Mammalian 1-carboxy substituted tetrahydroisoquinolines are represented by salsoline-1-carboxylic acid and 3',4'-deoxynorlaudanosoline carboxylic acid produced in phenylketonurics. Attempts have been made to prepare the optical isomers of these carboxylic acids and to determine their configuration by X-ray analysis. Configurational assignments were made for (-)- and (+)-salsoline-1-carboxylic acid and for (-)- and (+)- salsolinol-1-carboxylic acids prepared from the former by O-demethylation. Racemic and optically active salsoline and isosalsolines were prepared to study enzymic O-demethylation.
