20668-28-4Relevant articles and documents
Ruthenium-catalysed synthesis of 2- and 3-substituted quinolines from anilines and 1,3-diols
Monrad, Rune Nygaard,Madsen, Robert
experimental part, p. 610 - 615 (2011/02/28)
A straightforward synthesis of substituted quinolines is described by cyclocondensation of anilines with 1,3-diols. The reaction proceeds in mesitylene solution with catalytic amounts of RuCl3·xH 2O, PBu3 and MgBr2·OEt2. The transformation does not require any stoichiometric additives and only produces water and dihydrogen as byproducts. Anilines containing methyl, methoxy and chloro substituents as well as naphthylamines were shown to participate in the heterocyclisation. In the 1,3-diol a substituent was allowed in the 1- or the 2-position giving rise to 2- and 3-substituted quinolines, respectively. The best results were obtained with 2-alkyl substituted 1,3-diols to afford 3-alkylquinolines. The mechanism is believed to involve dehydrogenation of the 1,3-diol to the 3-hydroxyaldehyde which eliminates water to the corresponding α,β-unsaturated aldehyde. The latter then reacts with anilines in a similar fashion as observed in the Doebner-von Miller quinoline synthesis.
A Versatile New Synthesis of Quinolines and Related Fused Pyridines. Part 8. Conversion of Anilides into 3-Substituted Quinolines and into Quinoxalines
Meth-Cohn, Otto,Rhouati, Salah,Tarnowski, Brian,Robinson, Andrew
, p. 1537 - 1543 (2007/10/02)
Anilides (4) (ArNHCOCH2R) are readily converted into 2-chloro-3-R-quinolines (5) under Vilsmeier conditions and the 3-chloro-group may be removed with zinc and acetic acid yielding 3-substituted quinolines (7).When N-nitrosodialkylamines are used in place of dimethylformamide as the Vilsmeier agent, the anilides are converted into 2-chloroquinoxalines in low yields.Several by-products are formed and the mechanisms have been explored.Thus, the formation of ethyl N-arylcarbamate from the corresponding propionanilide is shown to involve an C->O alkyl migration related to a Wolff rearrangement, while N-arylformimidoyl dichloride (18), nitriles, and isocyanides are derived from C-C cleavage of the substituted side-chain.Variation of the acid chloride component of the Vilsmeier reagent or of the solvent was generally unproductive though use of phosphoryl bromide instead of the chloride caused conversion of anilides into bromoquinolines in low yields.
