Aza-C-nucleosides as a new class of nucleosides

The synthesis of a new type of nucleoside analogue, aza-C-nucleosides, has been accomplished by the reaction of a number of hydroxylated piperidine an d pyrrolidine derivatives with 5-bromouracil in pyridine. The conversion of the aza sugar (rt)-cis-N-benzyl-4-hydroxymethylpiperidin-3-ol ((+/-)-5a) i nto (+/-)-5b with trans-configuration was accomplished in five steps by suc cessive tritylatian, mesylation, S(N)2 reaction with sodium acetate, deacet ylation by treatment with sodium methoxide to give (+/-)-9 and finally detr itylation with 80% acetic acid to give (+/-)-5b.