SYNTHESIS OF SUBSTITUTED INDOLES AND PYRIMIDO[4,5-B]INDOLES BY DEHYDROGENATION OF TETRAHYDROINDOLES AND TETRAHYDROPYRIMIDOINDOLES

The synthesis of N1-substituted 2-amino-4,5,6,7-tetrahydroindole-3-car bonitriles 2 and 5,6,7,8-tetrahydropyrimido[4,5-b]-indoles 3-5 and the ir subsequent dehydrogenation to the corresponding 2-aminoindole-3-car bonitriles 8 and pyrimido[4,5-b]indoles 9, 11, 12, using DDQ in toluen e or palladium on charcoal in 1-methylnaphthalene, is described. Palla dium on charcoal proves to be a versatile reagent in dehydrogenation. The application of DDQ fails in the case of the 5,6,7,8-tetrahydropyri mido[4,5-b]indole-4-amines 4, 5, which are of special interest in rega rd of their affinity to the adenosine receptor. With sodium periodate, instead of the expected aromatization a new class of spiro-heterocycl es is formed.