Cyclization of Cyanoethylated Ketones as a Route to 6-Substituted Indole Derivatives

-Cyanoketones are quickly cyclized with KOtBu to 3-aminocyclohex-2-enone derivatives, which in turn will give substituted indoles when treated with oxalyl chloride. Thus, 3-amino-6,6-dimethylcyclohex-2-enone gave 3-chloro-6,6-dimethyl-2,5,6,7-tetrahydroindole-2,5-dione, whose structure was corroborated by X-ray crystallography, whereas the corresponding molecule without the blocking gem-dimethyl groups, 3-aminocyclohex-2-enone, gave via hydrogen shifts 6-chloro-3-hydroxyoxindole.