Homogeneous catalysis,heterogeneous recycling: a new family of branched molecules with hydrocarbon or fluorocarbon chains for the Friedländer synthesis of quinoline under solvent-free conditions

A new family of branched catalysts with hydrocarbon or fluorocarbon chains was used to catalyze Friedländer reaction between 2-aminoarylketones and α-methylene ketones under solvent-free conditions in good to excellent yields. The catalysts exhibit temperature-dependent solubility and such a thermomorphic character allows them to be recovered by filtration conveniently at room temperature and reused at least five times. To some extent, the branched catalysts with hydrocarbon chains are superior to those with fluorocarbon chains, as they are cheaper and more biodegradable.     

Tacrines as Therapeutic Agents for Alzheimer's Disease. V. Recent Developments

Herein we have reviewed our recent developments for the identification of new tacrine analogues for Alzheimer's disease (AD) therapy. Tacrine, the first cholinesterase inhibitor approved for AD treatment, did not stop the progression of AD, producing only some cognitive improvements, but exhibited secondary effects mainly due to its hepatotoxicity. Thus, the drug was withdrawn from the clinics administration. Since then, many publications have described non‐hepatotoxic tacrines, and in addition, important efforts have been made to design multitarget tacrines by combining their cholinesterase inhibition profile with the modulation of other biological targets involved in AD.     

Emerging Bottom-Up Strategies for the Synthesis of Graphene Nanoribbons and Related Structures

The solution-phase synthesis is one of the most promising strategies for the preparation of well-defined graphene nanoribbons (GNRs) in large scale. To prepare high quality, defect-free GNRs, cycloaromatization reactions need to be very efficient, proceed without side reaction and mild enough to accommodate the presence of various functional groups. In this Minireview, we present the latest synthetic approaches for the synthesis of GNRs and related structures, including alkyne benzannulation, photochemical cyclodehydrohalogenation, Mallory and Pd- and Ni-catalyzed reactions.     

Synthesis of Polysubstituted Quinolines Using Cyanuric Chloride as a Catalyst Under Aqueous Conditions

A mild, eco‐friendly and efficient route for the synthesis of quinolines and polycyclic quinolines via Friedländer annulation using cyanuric chloride as a catalyst under aqueous conditions is described.     

Solvent-free synthesis of dibenzo[b,j][1,10]phenanthroline derivatives using Eaton’s reagent as catalyst

A new class of dibenzo[b,j][1,10]phenanthrolines has been prepared. The synthon acridones were achieved in very good yield by a one-pot reaction of 2-amino-5-chloro or 2′-chloro/flouro-substituted benzophenones with 1,2-cyclohexanedione in the presence of freshly prepared Eaton’s reagent (phosphorus pentoxide–methanesulfonic acid) without solvent, through Friedländer synthesis. Then these intermediates were reacted with 2-amino-3,5-dibromobenzaldehyde to afford 1,3-dibromo-10-chloro-8-aryl-6,7-dihydrodibenzo[b,j][1,10]phenanthroline. Also an one-pot reaction between 2?mol of 2-amino-5-chloro aryl benzophenones with 1?mol of 1,2-cyclohexanedione to get 3,10-dichloro-5,8-diaryl-6,7-dihydrodibenzo[b,j][1,10]phenanthroline has also been reported. The newly synthesized structures of the compounds were deduced by spectroscopic techniques.     

Synthesis and X-ray structures of new cycloalka[e]pyrano[2,3-b]pyridine derivatives: novel tacrine analogues

A new series of tacrine (9-amino-1,2,3,4-tetrahydroacridine) analogues consisting of a cycloalka[e]pyrano[2,3-b]pyridine linked to a quinolyl ring has been synthesized. These compounds were prepared from the appropriately substituted pyran derivative via a Friedländer reaction with selected cycloalkanones in high yields. Single crystal X-ray structures are reported for four compounds.