A solution of dimethyl sulfate (2.0 equivalents) in CH2Cl2 was added to a solution of esomeprazole and DBU (1,8-diazabicyclo-[5.4.0]undec-7-ene, 1.2 equivalents) at room temperature. The mixture was then stirred while monitoring the reaction by thin-layer chromatography. After the reaction was complete, water was added to the reaction mixture and it was stirred vigorously for 30 minutes.
The mixture was then extracted with CH₂Cl₂, the organic layer was washed with 1N NaHCO₃ and water, dried over anhydrous MgSO₄, and concentrated on a rotary evaporator. The resulting oil was purified by short silica gel column chromatography (CH₂Cl₂ to 2% MeOH CH₂Cl₂ solution) to give OMeprazole N-Methyl 5-Methoxy Analog.
