Oxidation of 2'-deoxy-5-ethyl-4'-thiouridine with sodium meta-periodat
e yielded a separable mixture of (R) and(S)-sulfoxides. The structure
of the (R)-sulfoxide was confirmed by X-ray analysis. When treated wit
h sodium deuteroxide, the H-4' proton was exchanged for deuterium with
epimerisation at C-4'. Treatment of the deuteriated sulfoxide nucleos
ide with TFA/TMSBr furnished the starting material with H-4' replaced
by deuterium. (C) 1998 Elsevier Science Ltd. All rights reserved.