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. 2017 Jun 27;45(14):8142–8155. doi: 10.1093/nar/gkx558

Scheme 1.

Scheme 1.

Synthesis of dimeric r(UAM1U), r(UAM1A), r(AAM1A) and r(AAM1U) phosphoramidites.a. a Steps: (A) trifluoroacetic acid, THF, H2O, 0°C, 4 h, 92% (2a) and 92% (2b); (B) 4-methoxytrityl chloride, pyridine, 0°C to rt, 14 h, 85% (3a) and 90% (3b); (C) OsO4, 4-methylmorpholine N-oxide, dioxane, rt, 10 h, then NaIO4 in water, rt, 12 h, 95% (4a) and 98% (4b); (D) NaClO4, NaH2PO4, 2-methylbut-2-ene, t-BuOH, THF water, rt, 1 h, 82% (5a) and 92% (5b); (E) O-benzotriazole-N,N,N′,N′-tetramethyluroniumhexafluoro phosphate (HBTU), 1-hydroxybenzotriazole (HOBt), diisopropylethylamine, CH2Cl2, rt, 12 h, 89% (7c) and 97% (7d); (F) P(OCH2CH2CN)(N(iPr)2)2, tetrazole, CH2Cl2, rt, 7 h, 76%, (8c) and 85% (8d).