1.2 dimethyl 1,2,3,4 tetrahydroisoquinoline synthesis

Miyake and co-workers (40) have published a synthesis of ellipticine that features a novel reductive phenylation of nitroarenes (41) (Scheme 4). Nitration of 5,8-dimethyl-l, 2,3,4-tetrahydroisoquinoline (22) gave an inseparable mixture of nitro compounds 23. Treatment of this mixture with iron pentacarbonyl and triflic acid in the presence of benzene gave a 2 1 mixture of amines 24 and 25. Separation of these isomers and diazotization of each with nitrous acid, conversion to the azide, and thermolysis yielded ellipticine (1) and isoellipticine (27) (5,11-dimethyl-10f/-pyrido[3,4- )]carbazole), respectively, following Pd/C dehydrogenation of the initially formed nitrene insertion product (e.g., 26). The overall yield of ellipticine is 9%. 

Scheme 6.6 Synthesis of 1,2 dimethyl 1,2,3,4 tetrahydroisoquinoline via iridium catalyzed asymmetric hydrogenation.

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