在多烯的酸催化环化反应中,类似于Ⅰ的结构的单萜类衍生物的酸催化环化产物通常均为α-和β-异构体的混合物,如由柠檬酸制备环柠檬醛,由伪紫罗兰酮制备紫罗兰酮,…….虽然依具体反应条件的不同,两种异构体的比例可以有所改变,但欲得到无双键异构的单一产物往往比较困难. In the acid-catalyzed cyclization of polyenes, the acid-catalyzed cyclization products of monoterpene derivatives analogous to the structure of I are generally both mixtures of α- and β-isomers, such as the preparation of cyclocitral from citric acid , The preparation of ionone from Pion, ... Although the ratio of the two isomers may vary depending on the specific reaction conditions, it is often difficult to obtain a single product without double bond isomerization.