Solvent effects on isomer distributions in acylation of 1,2,3,4-tetramethyldibenzofuran: regiospecific solvation of the intermediate σ-complex
作者:Takashi Keumi、Yumiko Yagi、Yōkō Kato、Rikio Taniguchi、Makoto Tempōrin、Hidehiko Kitajima
DOI:10.1039/p29840000799
日期:——
large solvent effect is observed in Friedel–Crafts acylation of 1,2,3,4-tetramethyldibenzofuran (TMD). 8-Acyl-TMD is by far the major product in nitrohydrocarbons while 7-acyl-TMD is favoured in chloro-hydrocarbons and is the major product in many cases. The influence of temperature, and the nature of the reaction medium, acylating agents, and added nitro-compounds on the isomer distribution, are examined
1,2,3,4-四甲基二苯并呋喃(TMD)的Friedel-Crafts酰化反应中观察到了很大的溶剂作用。迄今为止,8-酰基-TMD是硝基烃中的主要产物,而7-酰基-TMD在氯代烃中是受欢迎的,并且在许多情况下是主要产物。详细检查了温度以及反应介质,酰化剂和添加的硝基化合物的性质对异构体分布的影响。结果表明,产物的重排,TMD的7位和8位之间的热力学差异,溶剂化不能降低酰基鎓离子的亲电性均不引起溶剂效应。硝基烃溶剂与导致8-酰基-TMD的中间体σ配合物的特定缔合被表示为反应途径。