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a -Cyano-o-toluonitrile is a-ethoxycarbonylated with ethyl chloroformate and 4-dimethylamino- pyridine, and cyclized to ethyl 3-amino-1-bromoisoquinoline-4-carboxylate. This is further functionalized, and examples of third-ring annulation to pyrimido [4,5-c] isoquinolines are reported.
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Deady et al. (1989) studied this question.
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