Synthesis of Substituted Indoles and Pyrimido[4,5-b]indoles by Dehydrogenation of Tetrahydroindoles and Tetrahydropyrimidoindoles

✍ Scribed by Eger, Kurt ;Lanzner, Wolfgang ;Rothenhäusler, Klaus

• Book ID: 102901919
• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 587 KB
• Volume: 1993
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199319930177

✦ Synopsis

Abstract

The synthesis of N^1^‐substituted 2‐amino‐4,5,6,7‐tetrahydroindole‐3‐carbonitriles 2 and 5,6,7,8‐tetrahydropyrimido[4,5‐b]‐indoles 3–5 and their subsequent dehydrogenation to the corresponding 2‐aminoindole‐3‐carbonitriles 8 and pyrimido[4,5‐b]indoles 9, 11, 12, using DDQ in toluene or palladium on charcoal in 1‐methylnaphthalene, is described. Palladium on charcoal proves to be a versatile reagent in dehydrogenation. The application of DDQ fails in the case of the 5,6,7,8‐tetrahydropyrimido[4,5‐b]indole‐4‐amines 4, 5, which are of special interest in regard of their affinity to the adenosine receptor. With sodium periodate, instead of the expected aromatization a new class of spiro‐heterocycles is formed.