Intramolecular meta photocycloaddition of conformationally restrained 5-phenylpent-1-enes. Part II: Steric and electronic effects caused by 4-mono- and 4-disubstitution
作者:Helma M. Barentsen、Alex B. Sieval、Jan Cornelisse
DOI:10.1016/0040-4020(95)00374-h
日期:1995.7
derivatives always prefer 2,6 addition, independent of the size of the substituent. For 2,6 addition two basic conformations are possible. Disubstituted compounds yield predominantly 1,3 addition with the sterically more demanding group exo. Except for the methoxymethyl and THF derivative the oxygen is found exo as a result of repulsion, while the monohydroxy derivative gives also endo which might be explained
已经研究了4-取代的5-苯基戊-1-烯10-18的间位光环加成反应。单取代的衍生物总是优选2,6-加成,而与取代基的大小无关。对于2,6加法,两个基本构型是可能的。双取代的化合物主要产生1,3加成,并且空间上要求更高的基团exo。除了甲氧基甲基和THF衍生物外,由于排斥作用还发现了氧的外泄,而单羟基衍生物也产生了内环,这可以用氢键解释。化合物11的产物主要从环己烷中的endo-OH变为甲醇中的主要exo-OH。发现与Diels-Alder环加成非常相似。