Synthese einiger 8‐substituierter 2‐Methyl‐1,2,3,4‐tetrahydroisochinoline

Synthesis of Some 8‐Substituted 2‐Methyl‐1,2,3,4‐tetrahydroisoquinolines A general route to 8‐substituted tetrahydroisoquinolines is exemplified by the preparation of the 2‐methyl‐1,2,3,4‐tetrahydroisoquinolin‐8‐ol ( 11 ), the ‐8‐carbaldehyde oxime ( 12 ) and the ‐8‐carbonitrile ( 13 ). It involves the conversion of isoquinoline ( 1 ) by partially modified Steps 1 , 2 , 3 , and 5 (see the Scheme ) into the 5‐bromo‐8‐nitro derivative 5 , reduction of the latter to the 8‐amino derivative 8 and replacement of the NH 2 ‐group with an appropriate substituent by a Sandmeyer ‐like reaction. The selective reductions of the N‐containing ring in 6 ( Steps 5 , 6 , and 8 ) and of the NO 2 ‐group in 5 ( Steps 4 and 7 ) were also studied.