Studies on Nucleosides and Nucleotides. VIII. Preparation and Reactions of Triphenylphosphoranediylnucleosides

Article abstract of DOI:10.1246/bcsj.53.3670

The reaction of uridine, N⁴-benzoylcitidine, guanosine, and N⁶-p-toluoyladenosine with diethyl azodicarboxylate and triphenylphosphine resulted in the formation of the corresponding 2',3'-O-(triphenylphosphoranediyl)cyclonucleosides.On the other hand, adenosine afforded, under similar conditions, 3',5'-O-(triphenylphosphoranediyl)adenosine (19).The difference can be explained in terms of the acidity of base moieties of the nucleosides.The reaction of 2',3'-O-(triphenylphosphoranediyl)-O²,5'-cyclouridine, N⁴-benzoyl-2',3'-O-(triphenylphosphoranediyl)-O²,5'-cyclocytidine, 2',3'-O-(triphenylphosphoranediyl)-N³,5'-cycloguanosine, or N⁶-p-toluoyl-2',3'-O-(triphenylphosphoranediyl)-N³,5'-cycloadenosine with nucleophiles and with electrophiles addorded the corresponding nucleoside derivatives with free 2'- and 3'-hydroxyl groups.Thus the 2',3'-O-triphenylphosphoranediyl group serves as a protecting group which is readily removed during work-up of the reaction products. 19 reacted with phenyl isocyanate to give 5'-O-phenylcarbamoyladenosine and N⁶,5'-O-bis(phenylcarbamoyl)adenosine.The reaction of 19 with diphenylketene also afforded acyladenosines with free 2'- and 3'-hydroxyl groups.These results suggested that 3',5'-O-triphenylphosphoranediyl group activates the 5'-carbon atom of adenosine.