Photo-Cleavage of Carbon-Carbon Bond of<b><i>α</i></b>-Iodocycloalkanones Giving<b><i>ω</i></b>,<b><i>ω</i></b>-Dialkoxyalkanoic Ester in Alcohol
作者:Shun-Jun Ji、C. Akira Horiuchi
DOI:10.1246/bcsj.73.1645
日期:2000.7
The irradiation at λ > 300 nm of α-iodocycloalkanones with a high-pressure mercury lamp in alcohols containing a small amount of water afforded the corresponding ω,ω-dialkoxyalkanoic ester (65—88%) by photochemical cleavage of the C(I)-C=O bond at room temperature. In the case of a commercial fluorescent lamp as the irradiating light source, photochemical ring-opening products were also obtained. The irradiation of 2α-iodo-5α- and 4β-iodo-5β-cholestan-3-ones in methanol gave methyl 2,2-dimethoxy-2,3-seco-5α-cholestan-3-oate and methyl 4,4-dimethoxy-3,4-seco-5β-cholestan-3-oate in 78 and 62% yields, respectively. The photochemical behavior of the cleavage reaction of α-iodocycloalkanones is also discussed on the basis of 2-hydroxycycloalkanone as an intermediate.
在含有少量水的醇中,用高压汞灯在 λ > 300 纳米波长下照射 α-碘环烷酮,可在室温下通过 C(I)-C=O 键的光化学裂解得到相应的 ω,ω- 二烷氧基烷酸酯(65-88%)。在使用商用荧光灯作为照射光源的情况下,也能获得光化学开环产物。在甲醇中辐照 2α-iodo-5α- 和 4β-iodo-5β-cholestan-3- 酮,可得到 2,2-二甲氧基-2,3-seco-5α-胆甾烷-3-酸甲酯和 4,4-二甲氧基-3,4-seco-5β-胆甾烷-3-酸甲酯,收率分别为 78% 和 62%。此外,还以 2-hydroxycycloalkanone 为中间体,讨论了 α-iodocycloalkanones 裂解反应的光化学行为。