title: Solution phase synthesis of short oligoribonucleotides on a precipitative tetrapodal support.
abstract: An effective method for the synthesis of short oligoribonucleotides in solution has been elaborated. Novel 2'-O-(2-cyanoethyl)-5'-O-(1-methoxy-1-methylethyl) protected ribonucleoside 3'-phosphoramidites have been prepared and their usefulness as building blocks in RNA synthesis on a soluble support has been demonstrated. As a proof of concept, a pentameric oligoribonucleotide, 3'-UUGCA-5', has been prepared on a precipitative tetrapodal tetrakis(4-azidomethylphenyl)pentaerythritol support. The 3'-terminal nucleoside was coupled to the support as a 3'-O-(4-pentynoyl) derivative by Cu(I) promoted 1,3-dipolar cycloaddition. Couplings were carried out with 1.5 equiv of the building block. In each coupling cycle, the small molecular reagents and byproducts were removed by two quantitative precipitations from MeOH, one after oxidation and the second after the 5'-deprotection. After completion of the chain assembly, treatment with triethylamine, ammonia and TBAF released the pentamer in high yields.
authors.affiliation: Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Turku, FI-20014, Turku, Finland.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gimenez Molina
authors.affiliation: Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Turku, FI-20014, Turku, Finland.
authors.forename: Amit M
authors.initials: AM
authors.lastname: Jabgunde
authors.affiliation: Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Turku, FI-20014, Turku, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Virta
authors.affiliation: Department of Chemistry, Faculty of Mathematics and Natural Sciences, University of Turku, FI-20014, Turku, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Lönnberg
keywords: nucleic acids; oligoribonucleotides; phosphoramidite; soluble support; synthesis