Reissert compound studies. XLII. Synthesis and reactions of the 3,4‐dihydro‐β‐carboline reissert compound and observations on α, β, and γ‐carbolines

3,4‐Dihydro‐β‐carboline and benzo[α]‐γ‐carboline yielded Reissert compounds. The 3,4‐dihydro‐β‐carboline Reissert compound, through its acid‐ and base‐promoted reactions, was found to be a very useful intermediate in the synthesis of several β‐carboline derivatives including tetracyclic compounds. Reaction of the 3,4‐dihydro‐β‐carboline Reissert compound with dichlorodicyanobenzoquinone (DDQ) resulted in the formation of l‐cyano‐β‐carboline thereby providing the first example of an oxidation of a Reissert compound with DDQ. α‐, β‐ and γ‐Carbolines failed to form Reissert compounds under a wide variety of conditions. 7‐Azaindole also failed to yield a Reissert compound.