The limitations of Combes reaction were reinvestigated. 4-(p-Chloroanilino)-3-penten-2-one (III), hitherto believed to be insusceptible to cyclodehydration in sulfuric acid, reacted at a higher temperature to give 2, 4-dimethyl-6-chloroquinoline (IV). 4-Anilino-3-buten-2-one (V), however, was sulfonated in concentrated sulfuric acid and no quinolines were detected in the reaction mixture. 4-(p-Chloroanilino)-3-buten-2-one (VI) was cyclodehydrated to give 6-chloroquinaldine (VIII) in dioxane containing sulfuric acid in low yield. β-Anilinoacrolein (X), a pussible reactant of Combes reaction, and its derivatives were synthesised for further studies, and their structure was confirmed by chemical evidences and by their infrared and nuclear magnetic resonance (NMR) spectra. The conformational analysis of β-arylaminoacroleins in three solvents was carried out using their NMR spectra.
Combes反应的局限性被重新研究。迄今为止认为在
硫酸中不易发生环化
脱水的4-(4-
氯苯胺基)-
3-戊烯-2-酮(III),在较高温度下反应生成了
2,4-二
甲基-
6-氯喹啉(IV)。然而,4-
苯胺基-3-
丁烯-2-
酮(V)在浓
硫酸中被磺化,反应混合物中未检测到
喹啉类化合物。4-(4-
氯苯胺基)-3-
丁烯-2-
酮(VI)在含有
硫酸的
二氧六环中环化
脱水,低产率地生成了6-
氯喹哪啶(VIII)。β-
苯胺基
丙烯醛(X),Combes反应的可能反应物及其衍
生物被合成以供进一步研究,并通过
化学证据和红外光谱、核磁共振(NMR)光谱确认了它们的结构。利用NMR光谱对β-芳胺基
丙烯醛在三种溶剂中的构象进行了分析。