Efficient synthesis of novel 9H-xanthen-9-yl derivatives of bidentate heterocyclic nucleophiles by Fe(HSO_4)_3 as a catalyst

We have demonstrated the direct substitution of 9H-xanthen-9-ol with different nucleophilic reagents such as thiazoles, triazoles, tetrazoles, hydrazines and hydrazinecarboxamides in good to high yields. This reaction catalyzed by ferric hydro- gensulfate as a heterogeneous acid catalyst in ethanol through SN1 type reaction of pyrylium with a nucleophilic reagent afforded the heterocycle- and aromatic-N-substituted xanthene derivatives as simple marked molecules in short reaction times.