Phosphorylation of alcohols with 5 was less facile. Treatment with an excess of methanol gives rise to the expected dimethyl pyrophosphate compound, 8, as well as a trifunc-tionalized tetraphosphate derivative 9 (Figure ). The corresponding diethylamino derivative of 9 was also observed as a minor impurity in the crude reaction of 5 with diethylamine, but this impurity was easily removed due to poor solubility in cold acetonitrile. However, we were unable to develop conditions for purification of 8 from 9. Treatment of 5 with more sterically demanding alcohols such as neopentanol and adenosine yielded only complex mixtures of products.