Synthesis of 2S 2 deoxy 2 C methylpurine nucleosides and their phosphoramidites

G. CABALLERO; M. GALLO; J.MONTSERRAT; A IRIBARREN

HELVETICA CHIMICA ACTA

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 1997 vol. 85 p. 1284 - 1294

0018-019X

We describe the stereoselective synthesis of (2S)-2-deoxy-2-C-methyladenosine (12) and (2S)-2-deoxy2-C-methylinosine (14) as well as their corresponding cyanoethyl phosphoramidites 16 and 19 from 6-O-(2,6-dichlorophenyl)inosine as starting material. The methyl group at the 2-position was introduced via a Wittig reaction ( 3, Scheme 1) followed by a stereoselective oxidation with OsO4 ( 4, Scheme 2). The primaryalcohol moiety of 4 was tosylated ( 5) and regioselectively reduced with NaBH4 ( 6). Subsequent reduction of the 2-alcohol moiety with Bu3SnH yielded stereoselectively the corresponding (2S)-2-deoxy-2-Cmethylnucleoside ( 8a).