220466-00-2Relevant academic research and scientific papers
p-Toluenesulfonic acid promoted annulation of 2-alkynylanilines with activated ketones: Efficient synthesis of 4-Alkyl-2, 3-disubstituted quinolines
Peng, Changlan,Wang, Yong,Liu, Lanying,Wang, Honggen,Zhao, Jiaji,Zhu, Qiang
supporting information; experimental part, p. 818 - 822 (2010/04/02)
Reactions between readily available 2-alkynylanilines and activated ketones such as ss-keto esters promoted by p-toluenesulfonic acid afford 4-alkyl-2, 3-disubstituted quinolines in good to excellent yields. The generality of substituents at the other end of the triple bond of 2-alkynylanilines makes the method a valuable approach to diversified 4-alkylquinolines, which are difficult to obtain by classical methods such as the Friedlaender reaction. Quinoline dimers can be prepared efficiently with alkyl or aryl linkers at C-4.
Biradicals from thermolysis of N-[2-(1-alkynyl)phenyl]-N'- phenylcarbodiimides and their subsequent transformations to 6H-indolo[2,3- b]quinolines
Shi, Chongsheng,Zhang, Quan,Wang, Kung K.
, p. 925 - 932 (2007/10/03)
Thermolysis of the carbodiimide 9a in γ-terpinene at 138 °C produced 2-(phenylamino)quinoline (11a, 49%) and the parent 6H-indolo[2,3-b]quinoline (14a, 16%). Apparently, 11a was produced via the biradical 10a followed by hydrogen-atom abstraction from γ-terpinene. A two-step biradical pathway through 12a or a one-step intramolecular Diels-Alder reaction could furnish 13a, which then underwent tautomerization to give 14a. With the carbodiimide 9b having a trimethylsilyl substituent at the acetylenic terminus, thermolysis in refluxing p-xylene at 138 °C produced the 6H-indolo[2,3- b]quinoline 14b (86%) exclusively. Treatment of 14b with 6 N NaOH in refluxing ethanol then furnished 14a in 92% yield. Similarly, the 6H- indolo[2,3-b]quinolines 14c-f were obtained from thermolysis of the carbodiimides 9c-f. The use of the aza-Wittig reaction between 4- methoxyphenyl isocyanate and the iminophosphoranes 2d and 2f to produce the corresponding carbodiimides followed by thermolysis furnished the 6H- indolo[2,3-b]quinolines 16d and 16f having a methoxy substituent at the C-2 position. Thermolysis of the carbodiimides 25a and 25b produced 26a and 26b having two indoloquinoline units connected at the 11 and 11' positions with either a three-carbon or a five-carbon tether. Using 1,4-phenylene diisocyanate for the aza-Wittig reaction with 2 equiv of the iminophosphorane 2g followed by thermolysis furnished 31 (66%) having two indoloquinoline units incorporated in the seven fused rings.
