Formation of 3-[amino(aryl)-methylidene]-1,3-dihydro-2 H -indol-2-ones involving ring transformation of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles
作者:Richard Kammel、Denisa Tarabová、Břetislav Brož、Veronika Hladíková、Jiří Hanusek
DOI:10.1016/j.tet.2017.02.045
日期:2017.4
starting 3-bromooxindole completely prevents formation of thiazoles. The prepared thiazoles 3b-f are unstable in solution and they undergo slow ring transformation to 2b-f. The rate limiting step of this rearrangement involves cleavage of an intermediary thiirane ring, which is slowed down by electron-withdrawing substituents on the thioamide (ρ = −1.15).
研究了3-溴代吲哚与取代的(杂)芳族硫代酰胺在乙腈中的反应。在室温下,该反应优选产生环转化的产物,即2-芳基-5-(2-氨基苯基)-4-羟基-1,3-噻唑(3b-f,h),而在高温下,则产生Eschenmoser偶联反应,即3- [氨基(芳基) -亚甲基] -1,3-二氢-2- ħ -吲哚-2-酮(2B-F ),是专门形成。只有两个例外(4-甲氧基和2-吡啶硫代酰胺),其中总是产生2a和2g的Eschenmoser偶联反应发生。也N起始3-溴恶吲哚的-甲基化完全防止了噻唑的形成。制备的噻唑3b-f在溶液中不稳定,并且经历缓慢的环转化为2b-f。该重排的速率限制步骤涉及中间硫杂环丁烷环的裂解,该硫杂环丁烷环被硫代酰胺上的吸电子取代基减慢了速度(ρ= -1.15)。