FLUOROPHOSPHATES AND 5'-H-PHOSPHONATES OF 2'-MODIFIED NUCLEOSIDES

A series of 5'-H-phosphonates and fluorophosphates of 2'-modified nucl eosides as potential antiviral agents was synthesized. 2'-Azido-2'-deo xy- or 2'-halogen-2'-deoxyribonucleosides and 2'-azido-2'-deoxyarabino nucleosides were coupled with phosphorous or fluorophosphoric acids us ing N,N'-dicyclohexylcarbodiimide or 2,4,6-triisopropylbenzensulfonyl chloride. 9-(2-Amino-2-deoxy-beta-D-arabinofuranosyl)adenine 5'-H-phos phonate and fluorophosphate were synthesized by reduction of the corre sponding 2'-azido derivatives with beta-mercaptoethanol. In the case o f 1-(2-amino-2-deoxy-beta-D-ribofuranosyl)uracil, the use of the N-ben zyloxycarbonyl protecting group instead of the N-trifluoroacetyl group during the transglycosylation was shown to give mainly the beta-anome r of 2'amino-2'-deoxyadenosine, thus considerably facilitating the syn thesis.