环庚三烯酮与邻二甲氧基苯在浓硫酸作用下的缩合重排反应机理

Mechanism of the condensation-rearrangement reactions of tropone with 1,2-dimethoxybenzene under the action of concentrated sulfuric acid

环庚三烯酮易发生环加成反应,偶尔有烯烃键上的取代反应.关于二甲氧基苯,多年来的主要关注点是其与不同醛或酮在强酸作用下的缩合反应,但多局限在芳基醛或饱和脂肪醛酮.本研究尝试多共轭不饱和酮与邻二甲氧基苯的缩合反应.结果发现在浓硫酸作用下环庚三烯酮不仅可以发生脱水缩合反应,更有趣的是环庚三烯酮在强酸及二甲氧基苯协同作用下可以发生重排缩环反应,由七元环收缩成六元芳香环.

The reactions of tropone（ cycloheptatrienone） gave the cycloaddition products frequently, and occasionally substitutions on the olefins bonds also occurred. For 1,2-dimethoxybenzene,previous studies concerned its condensation reactions with the different aldehydes or ketones,more limited to the aryl aldehydes or saturated aliphatic aldehydes and ketones,under the action of acid. We study the condensation reaction of conjugated polyene unsaturated ketone with o-dimethoxybenzene,and the results show that not only the dehydration condensation occurs under the action of acid,but also the interesting shrink ring rearrangement reaction occurs in which a seven-membered ring converts to a six-membered aromatic ring.