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GENERATION OF BIRADICALOIDS AND BIRADICALS BY PHOTOINDUCED ELECTRON TRANSFER

通过光致电子转移生成双自由基和双自由基

基本信息

批准号：
07640701
负责人：
TAKAHASHI Yasutake
金额：
$ 1.41万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Photoinduced electron transfer reaction of methoxy-substituted benzocyclobutanes results in their electrocycloreversion to generate omicron-xylylenes, which can be trapped with dienophiles such as tetracyanoethylene to produce cycloadducts. It is found that stereochemistry for the ring opening is non-stereospecific. Accordingly, photoinduced electron transfer presents a new and remarkable method for facile disrotatory ring opening of ring fused benzocyclobutanes. These derivatives do not undergo thermal ring opening because its symmetry allowed conrotaory process is sterically constrained.Photoinduced electron transfer reactions of 1,2-bis (1-phenylvinyl) benzene and 1,2-bis (1-phenylvinyl) furan have been investigated. These compounds undergo electron-transfer induced electrocyclization to generate an omicron-xylylene derivative and dimethylenefuran derivative When photolyzed with an electron-accepting sensitizer such as 9,10-dicyanoanthracene (DCA).Biradicaloid and biradical can be observed spectroscopically and trapped by dienophiles. It is clear that photoinduced electron transfer from 1,2-bis (1-phenylvinyl) benzene or 1,2-bis (1-phenylvinyl) furan to the singlet excited DCA is an important initial step. Substrate cation radicals in photogenerated ion radical pairs, [Substrate^<・+>, DCA^<・->] may undergo electrocyclization and omicron-xylylene and dimethylenefuran derivative can be produced by back ET possibly within the resulting ion pairs. The [4+2] cycloaddition of the resulting omicron-xylylene and dimethylenefuran derivative with added dienophiles leads to adducts.

甲氧基取代的苯并环丁烷的光诱导电子转移反应导致它们的电环化反转以生成omicron-二甲苯，其可以被亲二烯体如四氰基乙烯捕获以生成环加合物。发现开环的立体化学是非立体特异性的。因此，光诱导电子转移为苯并环丁烷的顺旋开环提供了一种新的方法。研究了1，2-双（1-苯基乙烯基）苯和1，2-双（1-苯基乙烯基）呋喃的光诱导电子转移反应。这些化合物在9，10-二氰基蒽（DCA）等受电子敏化剂的作用下发生电子转移诱导的电环化反应，生成邻苯二甲撑衍生物和二亚甲基呋喃衍生物，并可在光谱上观察到双自由基和双自由基，被亲双烯体捕获。很明显，光诱导电子从1，2-双（1-苯基乙烯基）苯或1，2-双（1-苯基乙烯基）呋喃到单重态激发的DCA的转移是重要的初始步骤。光生离子自由基对中的底物阳离子自由基，[底物^<·+>，DCA^<·->]可以经历电环化，并且可以通过可能在所得离子对内的反ET产生omicron-二甲苯基和二亚甲基呋喃衍生物。所得的omicron-亚二甲苯基和二亚甲基呋喃衍生物与添加的亲二烯体的[4+2]环加成导致加合物。