REMOVAL OF THE PYRROLIDINE SUBSTITUENT BY DEHYDROGENATION OF PYRROLIDIN-2-YL-3,4-DIHYDRO-TETRAHYDROISOQUINOLINE AND 1,2,3,4-TETRAHYDROISOQUINOLINE

Pyrrolidin-2-yl-groups located at C-4 of 3,4-dihydro- or 1,2,3,4-tetra hydroisoquinolines, respectively, are lost in the course of dehydrogen ation of these isoquinoline derivatives. However, acyclically substitu ted isoquinolines, hydrogenated in ring B, imethylaminoethyl)-1,2,3,4- tetrahydroisoquinoline, e.g., show loss of the amine group only by ben zylic cleavage, affording 4-ethylisoquinoline. Scope and limitation of this reaction are determined using specifically substituted isoquinol ines.