| 查看: 474 | 回复: 1 | |||
[求助]
各位大神，有谁可以帮助翻译此段文献，谢谢
|
|
However, investigation of the biological activities and opto-electric properties of these annulated polycyclic indolizines is still largely impeded by the lack of efficient and general synthetic methods. A few highly specific synthetic methods have been reported,butare rather lengthy and givelow over-all yields.16 Recently, isoindolo[2,1-a]quinolin-11-ones have been synthesized by [4+2] cycloadditions of acyliminium cation with alkenes.17Although [3+2] cycloaddition of pyridinium and quinolinium ylides has been applied for the synthesis of indolizines, these reactions were mainly limited to the use of electron deficient alkynes as dipolarophile.18In the case of alkenes, unstable tetrahydroindolizines are formed,which reversibly transform into a betaine intermediate followed by decomposition.19However, two recent approaches have succeeded in extending the [3+2] reaction to the application of alkenes as dipolarophiles. By using fluoroalkenes,fluoroiodoalkenes, and fluorinated vinyl tosylates20–22in the cycloadditions with the pyridinium and quinolinium ylides followed by elimination of hydrogen fluoride and toluenesulfonic acid, fluorinated and unfluorinated indolizines can be prepared. Meanwhile, Hu and co-workers reported that by using a mild dehydrogenative oxidant tetrakispyri- dinecobalt(II) dichromate [Py4Co(HCrO4)2] (TPCD), the tetrahydroindolizines can be in situ dehydrogenated to indo- lizines.23In this way, several 1,2-annulated indolizines were prepared by cycloadditions of pyridinium and quinolinium ylides with naphthoquinones, etc.24We report here a general and versatile synthesis of 1,2-annulated indolizines by one-pot tandem reactions of pyridinium, quinolinium, and isoquinolinium ylides with cyclic 1,2-dichloroalkenes 4–7. We have also shown that the reactions of the N-ylides with 2,3-dichloroindenone 4, 3,4-dichlorocoumarin 5, and 4a,6,7,8a-tetrachloro-1,4-methanonaphthalene-5,8-dione 6 proceed via [3+2] cycloaddition and elimination of two hydrogen chloride molecules, while the reactions of the N-ylides with 2,3-dichloro-1,4-naphthoquinone 7 take place by a novel mechanism involving sequential nucleophilic substitutions and a formal retro-Menschutkin reaction. By these one-pot tandem reactions of the N-ylides with 4–7,1,2-annulated, and1,2-,5,6-,and 1,2-,7,8-bisannulated polycyclic indolizine derivatives can be conveniently and regioselectively prepared from easily accessible starting materials. |
回复此楼» 猜你喜欢
聘U V热熔胶研究人员
已经有9人回复
-
职称评审没过，求安慰
已经有5人回复
-
垃圾破二本职称评审标准
已经有10人回复
-
投稿返修后收到这样的回复，还有希望吗
已经有8人回复
-
三无产品还有机会吗
已经有6人回复
-
博士申请都是内定的吗？
已经有14人回复
-
谈谈两天一夜的“延安行”
已经有13人回复
-
氨基封端PDMS和HDI反应快速固化
已经有11人回复
-
论文投稿求助
已经有4人回复
-
Applied Surface Science 这个期刊。有哪位虫友投过的能把word模板发给我参考一下嘛
已经有3人回复
★
RXMCDM: 金币+1 2014-04-25 10:09:26
RXMCDM: 金币+1 2014-04-25 10:09:26
|
本帖内容被屏蔽 |
2楼2014-04-25 09:05:09