abstract |
A process for the production of D- or L- or D, L-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid is described. It consists in cyclizing phenylalaninalkyl esters with formaldehyde in trifluoroacetic acid to give the corresponding 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid ester and then saponifying it to give the corresponding 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. |