Kinetics and mechanism of the base-catalyzed oxygenation of 1H-2-phenyl-3-hydroxy-4-oxoquinolines in DMSO/H2O
作者:Miklós Czaun、Gábor Speier、József Kaizer、Nadia El Bakkali-Taheri、Etelka Farkas
DOI:10.1016/j.tet.2013.05.117
日期:2013.8
The oxygenation of 4′-substituted 1H-2-phenyl-3-hydroxy-4-oxoquinolines (PhquinH2) in a DMSO/H2O (50/50) solution leads to the cleavage products at the C2–C3 bond in about 75% yield at room temperature. The oxygenation, deduced from the product compositions, has two main pathways, one proceeding via an endoperoxide leading to CO-release, and the other through a 1,2-dioxetane intermediate without CO-loss
在DMSO / H 2 O(50/50)溶液中4'-取代的1 H -2-苯基-3-羟基-4-氧代喹啉(PhquinH 2)的氧合导致C2-C3键处的裂解产物在室温下约75%的收率。由产物组合物推导的氧合作用有两个主要途径,一个途径是通过导致CO释放的内过氧化物进行,另一个途径是通过没有CO损失的1,2-二氧杂环丁烷中间体。该反应是特定的碱催化反应,动力学测量导致速率定律-ⅆ[PhquinH2个]/ⅆŤ=ķ哦-[OH - ] [PhquinH 2 ] [0 2 ]。速率常数,激活焓和303.16 K时的熵如下:ķ哦-=(2.42±0.03)×103摩尔-2个大号2个s-1个;Δ ģ ‡ = 73.13±4.02千焦耳摩尔-1 ; Δ ħ ‡ = 70.60±4.04千焦耳摩尔-1 ; Δ小号‡ = -28±2焦耳摩尔-1 ķ -1。该反应符合4'-取代底物的Hammett线性自由能关系,并且电子释放基团使氧合反应更快(ρ