Dimethyl Sulfate → 7-Methyl-7,8-dihydroguanosine-5'-diphosphate

Participants

Reaction Steps

In a clean, dry 2000 mL round bottom flask equipped with a stifling bar and under a stream of argon slowly dissolve dry and finely powdered guanosine 5′-diphosphate (1), (10.0 g, 20.5 mmol), either in free acid or sodium as a counter ion form, in 200 mL water, adjusting pH to 4.0 with glacial acetic acid. Dimethyl sulfate (20 mL, 119.04 mmol) was then added over a period of one hour with constant stirring at room temperature and the reaction continued for an additional hour during which time a decrease in pH was observed but pH was kept between pH 3.8 to 4.0 by drop-wise addition of 10 mM NaOH and methylation was monitored by analytical HPLC for progress. Methylation was determined to be 98% complete within 2 hr. After 2 hr, the reaction mixture was extracted with CHCl3 (3×200 mL) to remove unreacted excess dimethyl sulfate.

Provenance & Evidence