The synthesis of 2'-O-[(Triisopropylsilyl)oxy] methyl (TOM) phosphoramidites of methylated ribonucleosides (m1G, m2G, m22G, m1I, m3U, m4C, m6A, m62A) for use in automated RNA solid-phase synthesis

The straightforward synthesis of eight methylated ribonucleoside phosphoramidites is described. These building blocks allow for incorporation of the naturally occuring nucleosides 1-methylguanosine (m 1 G), N2-methylguanosine (m 2 G), N2,N2-dimethylguanosine (m 2 2 G), 1-methylinosine (m 1 I), 3-methyluridine (m 3 U), N4-methylcytidine (m 4 C), N6-methyladenosine (m 6 A), and N6,N6-dimethyladenosine (m 6 2 A) into oligoribonucleotides by automated RNA solid-phase synthesis. In all cases, the ribose 2′-hydroxyl group of the building blocks is masked by the recently introduced [(triisopropylsilyl)oxy]methyl (TOM) group.