An attempt was made to extend the established enamine reactions of I, 2-dihydroisoquinolines to the I, 2-dihydro-beta-carboline ring system, in the hope of preparing various 4-substituted beta-carbolines for pharmacological testing. Several substituted beta-carbolinium salts were prepared and subjected to attempted partial reduction to the 1,2-dihydro- species, but subsequent reaction with a base and an acid halide or with an acid and an aromatic aldehyde failed to yield the required products. Attempts to synthesise substituted beta-carbolines from 2-indole-aminoacetals (via the intermediate dihydro-compound) met with more success. Cyclisation of the acetals in the presence of an aromatic aldehyde and an acid gave the requred product in two out of four cases. A larger range of aldehydes were not investigated. An investigation was carried out into the cyclisation of 3-indole-aminoacetals to beta-carbolines. The results obtained were at variance with the published data, but no firm conclusions could be made concerning the cause of the discrepancies. Although only moderately successful in its original aims, the work described in this thesis led to the synthesis of several new carboline and indole derivatives and provided two possible routes to 4-substituted-beta-carbolines.
|Date of Award||1983|