Synthesis of 2′-Substituted Inosine Analogs via Unusual Masking of the 6-Hydroxyl Group
摘要:
2'-Modified inosine analogs have been synthesized from 6-chloropurine riboside via 6-dimethylaminopurine or 6-benzyloxypurine intermediates. The dimethylaminopurine intermediate was obtained via an unusually facile dimethylamine transfer from dimethylformamide.
Silylating reagents having a group other than a divalent oxygen separating two silyl groups provide regioselective protection of reactive groups under robust conditions, such as basic conditions used in alkylation, acylation and deoxygenation. In particular, silylating reagents having a group other than oxygen separating two silyl groups are useful for protecting two hydroxy groups of a ribonucleic or deoxyribonucleic acid. Alkylation of a 2′-hydroxy group of a ribonucleoside protected with the inventive silylating agents in the presence of an excess of a mild hindered base such as sodium HMDS may be carried out without protecting the exocyclic amine and oxo functionalities of nucleobases.
作者:Suetying Chow、Ke Wen、Yogesh S. Sanghvi、Emmanuel A. Theodorakis
DOI:10.1016/s0960-894x(03)00291-9
日期:2003.5
An efficient and chemoselective synthesis of 2'-O-methylguanosine (6) has been accomplished in high yield without protection of the guanine base. The salient feature of the synthesis of 6 lies in the application of methylene-bis-(diisopropylsilyl chloride), (MDPSCl(2), 2) as a new 3',5'-O-protecting group for nucleosides. Use of CH(3)Cl as a weak electrophile and NaHMDS as a mild base was crucial to
MDPSCL<sub>2</sub>: A New Protecting Group for Chemoselective Synthesis of 2′-<i>O</i>-Alkylated Guanosines
作者:Suetying Chow、Ke Wen、Yogesh S. Sanghvi、Emmanuel A. Theodorakis
DOI:10.1081/ncn-120021959
日期:2003.10
An improved strategy for the synthesis of 2'-O-methyl-guanosine (6) and 2'-MOE-guanosine (8) is reported. The regioselectivity of the alkylation was attained using a novel silicon-based protecting group, methylene-bis (diiso-propyl-silylchloride) (MDPSCl2, 2). The alkylation proceeded in a chemoselective manner using NaHMDS as the base and MeCl or MOE-Br as the appropriate electrophiles.
Synthesis of 2‘-<i>O</i>-Methoxyethylguanosine Using a Novel Silicon-Based Protecting Group
作者:Ke Wen、Suetying Chow、Yogesh S. Sanghvi、Emmanuel A. Theodorakis
DOI:10.1021/jo025970e
日期:2002.11.1
A short and efficient synthesis of 2'-O-methoxyethylguanosine (8) is described. Central to this strategy is the development of a novel silicon-based protecting group (MDPSCl(2), 2) used to protect the 3',5'-hydroxyl groups of the ribose. Silylation of guanosine with 2 proceeded with excellent regioselectivity and in 79% yield. Alkylation of the 2'-hydroxyl group of 6 proceeded with methoxyethyl bromide