PHOSPHORYLATION OF NUCLEOSIDES WITH PHOSPHORUS OXYCHLORIDE IN TRIALKYL PHOSPHATE

The reaction of guanosine and triethyl phosphate at 50 degrees C for 1 5 min produced the guanosine-triethyl phosphate complex in which triet hyl phosphate is coordinated to guanosine of high-anti form in a 1:1 m olar ratio, During the conversion of guanosine to guanosine 5'-monopho sphate with phosphorus oxychloride, the guanosine-triethyl phosphate c omplex showed excellent selectivity and high reactivity toward phospho rus oxychloride compared with those of guanosine, The rate of selectiv e phosphorylation of guanosine into guanosine 5'-monophosphate was mar kedly improved by preheating the mixture of guanosine and triethyl pho sphate at 50 degrees C, followed by adding phosphorus oxychloride to t he mixture at 0 degrees C, Thus, the 5'-phosphorylation of guanosine w ith phosphorus oxychloride in triethyl phosphate is considered to prog ress via the guanosine-triethyl phosphate complex as the reaction inte rmediate,