Theoretical studies on the glucosidation mechanism of 6-(4-halophenyl)-3(2H)-pyridazinone

The glucosidation of 6-(4-halophenyl)-3(2H)-pyridazinone engenders two isomers, O-glucoside and N-glucoside. In order to find appropriate methods to obtain different glucosides, density functional theory (DFT) calculation at B3LYP/6-31G(d) level was employed to explore the mechanisms of two processes including Koenigs-Knorr reaction and phase-transfer catalysis reaction of 6-(4-halophenyl)-3(2H)-pyridazinone glucosidation. The calculation results reveal that both processes are SN2 reaction, in which O-glucosides are kinetic products and N-glucosides are thermodynamic products. That O-glucosides were main products in Koenigs-Knorr reaction is due to the assistance of sliver ions, which bond to 2-N of pyridazinone and prevent the transforming from O-glucosides to N-glucosides.