Intramolecular Mannich Reaction of 2-Oxotryptamines with Acetone Yielding Spiro[indole-3,3'-pyrrolidin]-2-ones
2-Oxotryptamines undergo intramolecular Mannich-type cyclization with acetone to give 2',2'-dimethylspiro[indole-3,3'-pyrrolidin]-2-ones. In presence of an alkylating reagent, this reaction gives the corresponding 1'-substituted products.