A PRACTICAL SYNTHESIS OF N1-METHYL-2'-DEOXY-PSI-URZDINE (PSI-THYMIDINE) AND ITS INCORPORATION INTO G-RICH TRIPLE-HELIX FORMING OLIGONUCLEOTIDES

A convenient synthesis of N1-methyl-2'-deoxy-psi-uridine (psi-thymidin e, psi T, 7a) has been accomplished in good yield. The structural conf ormation of 7a was derived by 2D NMR and 1D NOE experiments. The nucle oside 7a has been incorporated into G-rich tripler forming oligonucleo tides (TFOs) by solid-support, phosphoramidite method. The tripler for ming capabilities of the modified TFOs (S4, S5 and S6) containing psi T has been evaluated in antiparallel motif with a target duplex (duple x-31) GCCAGTGAC)3'-5d(GACTCTGGCCCTTCCTCCTTCCCGGTCACTG)3' (D1) at pH 7. 6. The tripler formation of modified homopyrimidine-oligomers (S1, S2 and S3) has also been studied in parallel motif with a duplex-10 (A(10 ):T-10) at pH 7.0.