Development of more potent 4-dimethylaminopyridine analogues

The syntheses of bicyclic diaminopyridines 3 and 4 and tricyclic triaminopyridines 5 and 6, two novel series of nucleophilic catalysts, are described. Arguments are made for predicting the superiority of these catalysts over DMAP and even 2, the best esterification catalyst reported to date. The efficiencies of DMAP, PPY, and 2-6 in catalyzing the esterification of tertiary alcohols were compared. As predicted, 5 and 6 were about 6-fold more effective than DMAP and slightly better than 2.