[Selective dopamine D-2 autoreceptor agonists with 8-azaindole substructure: synthesis and theoretical studies]

Starting from the 1,3-dipolar cycloaddition product 6a the peri-fused beta-ketoester 7 is prepared. 7 is employed as a key intermediate for the synthesis of the D-2 autoreceptor agonist 5. Two alternative approaches are used for installing the amino function: electrophilic amination and Curtius rearrangement. The distribution of charge of the aromatic moiety of 5 has been determined by molecular orbital calculations and compared to the respective values of the ergolines. The results of ab-initio calculations and semi-empirical methods have been compared.