Amino-grafted mesoporous materials based on MCF structure involved in the quinoline synthesis. Mechanistic insights

Porous carbons-derived from vegetal biomass in the synthesis of quinoxalines. Mechanistic insights

“…Two interesting finding were found for the uncatalyzed reaction: (1) initial reactant complex is formed, in which both reagents interact by intra-and intermolecular H-bonds, favoring the approaching of the reagents, and (2) the involvement of one water molecule in TSI1-I2, TSI2-I3 and TSI3-I4 notably decreasing the activation barrier (from 46.1 to 13.0 kcal mol -1 for TSI1-I2 and TSI1-I2w, respectively). This fact has been previously observed by the authors in dehydration and heterocyclization reactions since water molecules can act as bifunctional acid-base catalyst [40,41]. In the same context, the reactant complex formation is also observed for the catalyzed processes in which the acidic proton of the catalysts is H-bounded to the carbonyl acceptor and to the adjacent amine function.…”

Highly Efficient and Selective Catalytic Synthesis of Quinolines Involving Transition‐Metal‐Doped Carbon Aerogels

“…In this context, carbon aerogels emerge as interesting environmental friendly catalysts. The enhanced catalytic performance of RFCoS aerogel as compared with that of mesoporous silicas recently reported for the synthesis of quinoline 3 a are also remarkable. The reaction catalyzed by RFCoS sample yielded quinoline 3 a in 93 % (1 h), whereas in the presence of MCF and NbMCF 3 a was obtained with lower yields, 40 and 86 %, respectively, at higher reaction times (3 h).…”

“…In this regard, Friedländer condensation promoted by porous catalytic systems is an interesting research line. The synthesis of quinolines, by Friedländer reaction, was recently reported to be efficiently catalyzed by zeolites, acid, basic or bifunctional mesoporous silica, metal–organic frameworks such as CuBTC and acid carbon materials, and others. We later reported an experimental and theoretical study concerning the selective synthesis of several nitrogen heterocycles under mild reaction conditions, catalyzed by carbon hybrid materials with basic properties …”

Porous Catalytic Systems in the Synthesis of Bioactive Heterocycles and Related Compounds

“…More recently, Smuszkiewicz et al have reported a new series of ordered amino-grafted mesoporous metallosilicates based on MCF structures, which have been found to successfully catalyze the total selective synthesis of quinolines 57, via Friedländer reaction, from 2-amino-5-chlorobenzaldehyde and ethyl acetoacetate (Scheme 39) [149,150]. Experimental and theoretical studies demonstrated that the presence of water in nonactivated samples plays an important role in the formation of the corresponding quinoline by stabilizing key transition structures and intermediate species and enhancing the regioselectivity of the reaction.…”