CARBON DIOXIDE: A REAGENT FOR THE PROTECTION OF NUCLEOPHILIC CENTRES AND THE SIMULTANEOUS ACTIVATION OF ALTERNATIVE LOCATIONS TO ELECTROPHILIC ATTACK. PART I. A NEW SYNTHETIC METHOD FOR THE 2-SUBSTITUTION OF 1-UNSUBSTITUTED INDOLES.

Article abstract of DOI:10.1016/S0040-4039(00)98265-0

Indole was converted into several 2-substituted derivatives by using carbon dioxide both for N-protection and to give an intermediate carbanion stabilizing group. t-Butyllithium was used as a lithiating agent at the alpha-carbon atom of the indole enamino group.The resulting 2-substituted indole-1-carboxylic acids underwent smooth thermal decarboxylation under mild conditions.Alternatively, with longer reaction times the protecting group is lost during the reaction.