Research on imidazo[2,1-?]isoquinoline derivatives. 2. Synthesis and transformations of esters of the imidazo[2,1-?]isoquinoline series

Abstract

The action of α-halo keto acid esters on 1-aminoisoquinoline was used to synthesize 2- and 3-alkoxycarbonylimidazo[2,1-α]isoquinolines. The 2-ethoxycarbonyl and 2-ethoxycarbonylmethyl derivatives display the typical properties of esters and readily undergo electrophilic substitution (chlorination and bromination) in the 3 position of the system. 3-Alkoxycarbonyl-substituted compounds in which the ester group is attached to the carbon atom with increased electron density do not react with amines; the acid hydrolysis of these compounds is accompanied by elimination of carbon dioxide. Under radical bromination conditions the 3-ethoxycarbonyl-2-methyl derivative is brominated in the methyl group to give monobromoand dibromo-substituted compounds.