The influence of temperature on the reaction of dichlorodicyanoquinone (DDQ) with l,2,3,4-tetrahydro-/3carbolines has been explored. The DDQ oxidation of amide 2a, when performed at room temperature, gave 3a (3-acylindole)/4 (2-acylindole) in a ratio of ca. 1:1, while this was increased to 2:1 at 0 °C and to ca. 5:1 at -78 °C. This method for preparation of 4-oxo-/3-carbolines has been employed for synthesis of the /3-carboline alkaloid crenatine (11). In addition, treatment of the 4-oxotetrahydro-/3-carboline (3b) with hydrazine gave l-ethyl-4amino-/3-carboline (12) which should provide access to a series of 4-substituted /3-carbolines.

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Die Selendioxid‐Oxidation des Tetrahydro‐β‐carbolins (I) führt zu einem Gemisch der vier Verbindungen (II) bis (V), während aus dem N‐Benzoylderivat (VI) nur das Ketoamid (VII) gebildet wird.

Die Oxidation von Piperidinindolen mit SeO2 wird beschrieben.