2'-Deoxyguanosine (1)(32.5 g, 120 mmoles) was dried three times by co-evaporation with dried pyridine and suspended in 700 ml of dry pyridine. To this suspension at 0° C. trimethylsilyl chloride (80 ml, 600 mmoles) was added and the mixture stirred at 0° C. for 1 hour. Phenylacetyl chloride (80 ml, 600 mmoles) was added dropwise and the solution stirred for 15 hours. The reaction mixture was then cooled in an ice bath and 150 ml of cold water was added. After 30 minutes, 150 ml of 29% aqueous ammonia was added and the mixture stirred for 30 minutes. The solution was then evaporated to near dryness and the residue dissolved in 700 ml water and 700 ml methylene chloride. The product crystallized out of the aqueous solution upon extraction with CH2Cl2 was filtered off, washed with CH2Cl2 (3×70 ml) and ether (3×70 ml) and air dried to yield 27 g (56%) of N2 -(phenylacetyl)-2'-deoxyguanosine (2a), as confirmed by spectroscopic and elemental analysis.
