The 4-(N-Dichloroacetyl-N-methylamino)benzyloxymethyl Group for 2'-Hydroxyl Protection of Ribonucleosides in the Solid-Phase Synthesis of Oligoribonucleotides
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- 作者：Jacek Cielak ; Andrzej Grajkowski ; Jon S. Kauffman ; Robert J. Duff ; Serge L. Beaucage
- 刊名：Journal of Organic Chemistry
- 出版年：2008
- 出版时间：April 4, 2008
- 年：2008
- 卷：73
- 期：7
- 页码：2774 - 2783
- 全文大小：189K
- 年卷期：v.73,no.7(April 4, 2008)
- ISSN：1520-6904
文摘
Emerging RNA-based technologies for controlling gene expression have triggered a high demand forsynthetic oligoribonucleotides and have motivated the development of ribonucleoside phosphoramiditesthat would exhibit coupling kinetics and coupling efficiencies comparable to those of deoxyribonucleosidephosphoramidites. To fulfill these needs, the novel 4-(N-dichloroacetyl-N-methylamino)benzyloxymethylgroup for 2'-hydroxyl protection of ribonucleoside phosphoramidites 9a-d has been implemented (Schemes1 and 2). The solid-phase synthesis of AUCCGUAGCUAACGUCAUGG was then carried out employing9a-d as 0.2 M solutions in dry MeCN and 5-benzylthio-1H-tetrazole as an activator. The couplingefficiency of 9a-d averaged 99% within a coupling time of 180 s. Following removal of all base-sensitive protecting groups, cleavage of the remaining 2'-[4-(N-methylamino)benzyl] acetals from theRNA oligonucleotide was effected in buffered 0.1 M AcOH (pH 3.8) within 30 min at 90 
C. RP-HPLCand PAGE analyses of the fully deprotected AUCCGUAGCUAACGUCAUGG were comparable to thoseof a commercial RNA oligonucleotide sharing an identical sequence. Enzymatic digestion of the RNAoligomer catalyzed by bovine spleen phosphodiesterase and bacterial alkaline phosphatase revealed nosignificant amounts of RNA fragments containing (2'
5')-internucleotidic phosphodiester linkages ornoteworthy nucleobase modifications.
C. RP-HPLCand PAGE analyses of the fully deprotected AUCCGUAGCUAACGUCAUGG were comparable to thoseof a commercial RNA oligonucleotide sharing an identical sequence. Enzymatic digestion of the RNAoligomer catalyzed by bovine spleen phosphodiesterase and bacterial alkaline phosphatase revealed nosignificant amounts of RNA fragments containing (2'5')-internucleotidic phosphodiester linkages ornoteworthy nucleobase modifications.