Rate measurements of certain Vilsmeier–Haack reactions. Part 3. The reactivities of various pyrrole substrates
作者:Julian White、George McGillivray
DOI:10.1039/p29840001179
日期:——
The rates of reaction of six pyrrole substrates with the Vilsmeier–Haack reagent derived from NN-dimethylbenzamide (and in some cases from N-benzoylmorpholine or NN-diethylbenzamide) and phosphoryl chloride were measured. The deactivating effect on substitution at the 5-position of a groups when present at the 2-and 4-position. This net activation of the substrate was lost when the bulkier Vilsmeier–Haack
测量了六种吡咯底物与衍生自NN-二甲基苯甲酰胺(在某些情况下源自N-苯甲酰基吗啉或NN-二乙基苯甲酰胺)和磷酰氯的Vilsmeier-Haack试剂的反应速率。当存在于2位和4位时,对基团5位取代的失活作用。当使用源自NN-二乙基苯甲酰胺的较大的Vilsmeier-Haack配合物时,底物的净活化作用消失了。在吡咯的1-位上甲基或苄基的存在导致底物的意外和非常显着的失活。建议试剂和底物在过渡状态下具有高度特异性的取向,以解决此问题。