Intramolecular [2+2] Photocycloaddition of Bichromophoric Derivatives of 3,5-Dihydroxybenzoic Acid and 3,5-Dihydroxybenzonitrile
作者:Norbert Hoffmann、Jean-Pierre Pete
DOI:10.1055/s-2001-15076
日期:——
The irradiation of 3-alkenyloxy-5-hydroxybenzoic acid derivatives 1a-d yields highly functionalized alkyloxyenone derivatives when the reaction is carried out in the presence of acid. A higher reactivity is observed for the corresponding 3-alkenyloxy-5-hydroxybenzonitrile compounds 7a, b, which also react in neutral reaction media. In the first step of the reaction, a [2+2] photocycloaddition occurs. The following steps, leading to stable final products, need acid catalysis in the case of the substrates 1a-d. The irradiation of the benzonitrile derivative 7b also furnishes the side product 9, which results from a [2+3] photocycloaddition.
3-烯丙氧基-5-羟基苯甲酸衍生物1a-d在酸性条件下进行辐照,可以得到高度官能团化的烯丙氧基烯酮衍生物。相应的3-烯丙氧基-5-羟基苯腈化合物7a, b在中性反应介质中也表现出更高的反应活性。反应的第一步是[2+2]光环加成。接下来的步骤,导致稳定最终产物的生成,对于底物1a-d需要酸催化。苯腈衍生物7b的辐照也得到了副产物9,这是从[2+3]光环加成得到的。