核苷2-硅基-5-己烯基自由基的5-外向与6-内向环化：6-(溴甲基)二甲基甲硅烷基1',2'-不饱和尿苷的反应

5-Exo versus 6-endo cyclization of nucleoside 2-sila-5-hexenyl radicals: reaction of 6-(bromomethyl)dimethylsilyl 1',2'-unsaturated uridines.

作者信息

Ogamino Junko, Mizunuma Hideaki, Kumamoto Hiroki, Takeda Shingo, Haraguchi Kazuhiro, Nakamura Kazuo T, Sugiyama Hiroshi, Tanaka Hiromichi

机构信息

School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.

出版信息

J Org Chem. 2005 Mar 4;70(5):1684-90. doi: 10.1021/jo040260p.

DOI:10.1021/jo040260p

PMID:15730288

Abstract

The mode of cyclization of 2-sila-5-hexen-1-yl radicals generated from 6-(bromomethyl)dimethylsilyl-1',2'-unsaturated uridines was investigated. In contrast to the case of the 2'-unsubstituted 6-silicon-tethered substrate (4), which undergoes exclusive 6-endo-cyclization, reactions of the 2'-substituted (Me, CO2Me, OBz, and Cl) derivatives (14, 20, 22, and 24) uniformly proceeded in preferential or exclusive 5-exo-mode. The Tamao oxidation of the resulting cyclized products was also carried out to synthesize the corresponding 1'-C-hydroxymethyl derivatives.

摘要

对由6-(溴甲基)二甲基甲硅烷基-1',2'-不饱和尿苷生成的2-硅杂-5-己烯-1-基自由基的环化模式进行了研究。与2'-未取代的6-硅连接底物(4)仅发生6-内型环化的情况不同，2'-取代(Me、CO2Me、OBz和Cl)衍生物(14、20、22和24)的反应均以优先或唯一的5-外型模式进行。还对所得环化产物进行了玉尾氧化反应，以合成相应的1'-C-羟甲基衍生物。