Purines, quaternization

N-Alkylated purines, especially compounds such as quaternized caffeine with a positive charge in the imidazole ring, are readily reduced by sodium borohydride to produce dihydro derivatives, reduction occurring in the charged imidazole ring (76TL1199, 76joc2303). 

A new purine synthesis is exempiifled by the condensation of 4-umino-l,3-dimethyl-S>nitrosouracil (1) with the reagent, a quaternized Munnich base, to give... 

Methylsulfonyl derivatives of the aminonucleoside moiety of puromycin were found to quaternize even more readily than 5 -O-p-tolylsulfonyladenosine derivatives.430 Thus, the 2, 3 -carbonate 166 or the N-(benzyloxycarbonyl) derivative of 9-[3-amino-3-deoxy-5-0-(methylsulfonyl) -/3 - D - ribofuranosyl] - 6 - (dimethylamino) purine cy-clized in high yield when kept at room temperature, or on boiling in chloroform solution for 2 hours the anhydronucleoside 167 was obtained in 91% yield, and this result established the /3-D-glycosidic linkage.430... 

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