Text this: TETRAHYDROISOQUINOLINES .2. SYNTHESIS OF 4-SUBSTITUTED N-METHYL-1,2,3,4-TETRAHYDROISOQUINOLINES VIA REGIOSELECTIVE AND STEREOSELECTIVE ELABORATION OF TRICARBONYL(N-METHYL-1,2,3,4-TETRAHYDROISOQUINOLINE)CHROMIUM