PROCESSES FOR THE DIASTEREOSELECTIVE SYNTHESIS OF CIS-NUCLEOSIDES AND NUCLEOSIDE ANALOGUES AND DERIVATIVES IN HIGH OPTICAL PURITY AND INTERMEDIATES USEFUL IN THOSE PROCESSES

摘要

Disclosed is a process for the diastereoselective synthesis of cis-nucleosides and nucleoside analogues and derivatives having the general formula (I) wherein R1 is hydrogen or acyl; R2 is a residual of a required purine or pyrimidine base; W is oxygen, sulphur, S=O or SO2, a group of the formula NZ or a CH2 group; X is oxygen, sulphur, S=O, SO2, a group of the formula NZ, a CH2 group, CHF, CH, CHN3 or CHOH; and Z is hydrogen, hydroxyl, alkyl or acyl, if Y is CH2 and X is oxygen, sulphur, S=O or SO2 than W is not oxygen, sulphur, S=O or SO2, commenced by glycosylation of a required purine or pyrimidine base or anologues or derivatives thereof. The glycosylation is processed by mere enentiomer of the compound with the formula (II) in which R3 is carboxyl, (C1 to C6)-alkoxycarbonyl, (C1 to C3)-alkyl carbonyl or phenyl carbonyl; and L is a removable group by using Lewis acid. Intermediates used during this process are also described.