Enamine chemistry. Part XX. Reactions of αβ-unsaturated acid chlorides. Synthesis of alkyl 2,6-dioxobicyclo[3.3.1]nonane-1-carboxylates, alkyl 2,9-dioxobicyclo[3.3.1]nonane-7-carboxylates, and 2,9-dioxobicyclo[3.3.1]nonane-7-carbonitriles

Abstract

Reactions of the pyrrolidine enamines of dialkyl 4-oxocyclohexane-1,1-dicarboxylates with acryloyl chloride give alkyl 2,6-dioxobicyclo[3.3.1]nonane-1-carboxylates, whereas the pyrrolidine enamines of ethyl 4-oxocyclohexane-1-carboxylate and ethyl 1-cyano-4-oxocyclohexane-1-carboxylate give ethyl 2,9-dioxobicyclo[3.3.1]nonane-7-carboxylates and 2,9-dioxobicyclo[3.3.1]nonane-7-carbonitriles, respectively. The reasons for this change in the course of the reaction are discussed. Distillation of the proline enamine of diethyl 4-oxocyclohexane-1,1-dicarboxylate gives a pyrrolo[1,2-a]indole derivative.