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 I-methylguanosine (m(1)G), N-2-methylguanosine (m(2)G), N-2,N-2-dimethylguanosine (m(2) (2)G), 1-methylinosine (m(1)I), 3-methyluridine (m(3)U), N-4-methylcytidine (m(4)C), N-6-methyladenosine (m(6)A), and N-6,N-6-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)oxyjmethyl (TOM) group.