A new "all-water" tandem arylaminoarylation/arylaminoalkylation–reduction–cyclisation route is reported for one-pot diversity oriented synthesis of regiodefined 1,2-disubstituted benzimidazoles. Water plays a crucial and indispensable role through hydrogen bond driven 'synergistic electrophile–nucleophile dual activation' in the formation N-mono-aryl/aryl alkyl/alkyl/cycloalkyl o-nitroanilines under metal base-free conditions to replace transition metal-based C–N (aryl amination) chemistry...

The catalytic potential of different fluoroboric acid-derived catalyst systems viz. aq HBF4, solid supported metal tetrafluoroborates (inorganic salts), tetrafluoroborates, and tetrafluoroborate based ionic liquids (organic salts) were investigated for the three component reaction (3-MCR) 1,2-diketone, aldehyde, ammonium salts to form 2,4,5-trisubstituted imidazoles four (4-MCR) involving amine acetate 1,2,4,5-tetrasubstituted imidazoles. HBF4–SiO2 was found be stand out both 3-MCR 4-MCR...

Hydrogen-bond-driven electrophilic activation for selectivity control during competitive formation of 1,2-disubstituted and 2-substituted benzimidazoles from o-phenylenediamine aldehydes is reported. The fluorous alcohols trifluoroethanol hexafluoro-2-propanol efficiently promote the cyclocondensation with to afford selectively at rt in short times. A mechanistic insight invoked by NMR, mass spectrometry, chemical studies rationalize selectivity. ability promoting reaction controlling can be...

A water-assisted tandem N-alkylation–reduction–condensation process has been devised as a new synthetic route for the one-pot synthesis of N-arylmethyl-2-substituted benzimidazoles. Water plays crucial and indispensable role through hydrogen bond mediated 'electrophile–nucleophile dual activation' in promoting selective N-monobenzylation o-nitroanilines an alternative to transition metal-based chemistry C–N formation (amination) forms basis disposing substituents on benzimidazole moiety...

The scope and limitations of surfactants as catalysts for the synthesis quinoxalines using microreactors made in water has been assessed. catalytic potential followed order: non-ionic > anionic Brønsted acid cationic surfactants. surfactant, Tween 40, is most effective catalyst affording excellent yields within a short reaction time at room temperature compatible with different variations 1,2-diketones 1,2-diamines. medium (spent water) containing catalyst, well itself (recovered 40) can be...

A novel strategy of 'all water chemistry' is reported for a concise total synthesis the class anti-anginal drug ranolazine in its racemic (RS) and enantiopure [(R) (S)] forms. The reactions at crucial stages are promoted by led to development new water-assisted chemistries (i) catalyst/base-free N-acylation amine with acyl anhydride, (ii) base-free chloride, (iii) one-pot tandem N-alkylation N-Boc deprotection, (iv) selective mono-alkylation diamine (e.g., piperazine). distinct advantages...

Benzothiazole-2-carboxyarylalkylamides are reported as a new class of potent anti-mycobacterial agents.

Cascade<italic>N</italic>-aroylmethylation–reduction–condensation process as novel strategy of “all water chemistry” for first generalized regioselective synthesis 2-aryl quinoxalines.

Selectivity control during the formation of 1,2-disubstituted benzimidazoles has been achieved for reaction o-phenylenediamine with aldehydes in presence solid supported protic acids as catalysts and choosing an appropriate medium. Perchloric acid adsorbed on silica-gel (HClO4–SiO2) was found to be most effective catalyst system synthesis EtOH at rt. Apart from solvent, electronic steric factors aldehyde factor are also significant contributory dictating selectivity. An understanding...

Three new, concise, and protecting group-free synthetic routes for (RS)- (S)-lubeluzole are reported in higher (46–62%) overall yields compared to the procedures (6–35%). The key steps involve C–N bond formation via epoxide aminolysis nucleophilic substitution of 2-chlorobenzothiazole with suitably designed precursor amines performed aqueous medium. Water offers an advantage promoting reactions organic solvents its role is envisaged as hydrogen-bond mediated electrophile–nucleophile dual activation.

Abstract A cascade organocatalysis is reported for the nucleophilic and electrophilic dual activation taking place in reaction of methyl ketones or active methylene compounds with DMF‐DMA ( N , ‐dimethylformamide dimethyl acetal). L ‐Proline serves as an efficient organocatalyst covalent noncovalent synchronous mode ambiphilic various aryl, heteroaryl, styryl ketones, cyclic 1,3‐diketones to achieve convenient syntheses versatile synthons (2 E...

A novel organocatalytic dual activation strategy is reported for an efficient synthesis of the versatile synthons (2E)-1-aryl/heteroaryl/styryl-3-(dimethylamino)prop-2-en-1-ones and α-(E)-[(dimethylamino)methylene]cycloalkanones. 2-Guanidinoacetic acid (10 mol%) serves as ambifunctional organocatalyst reaction various aryl/heteroaryl/styryl methyl ketones cyclic having α-methylene moiety with N,N-dimethyl­formamide dimethyl acetal at 100 ˚C 1-3 hours under solvent-free conditions to afford...

Abstract Optimum reaction conditions for the one‐pot two‐step synthesis of 2‐aryl quinoxalines in aqueous medium are studied.

Abstract This method is suitable for a variety of ketone substrates.

Abstract Water plays the crucial role of hydrogen bond mediated electrophile‐nucleophile dual activation during selective N‐monoalkylation nitroanilines that forms basis regiodefined installation substituents in their respective positions benzimidazole framework.

Abstract Optimized reaction conditions using 2‐guanidinoacetic acid as the catalyst are developed for condensation of methyl ketones or cycloketones with acetal (II) to give E‐isomers enaminones.

Abstract The regiodefined synthesis of title compounds (IV) via a tandem arylaminoarylation‐reduction‐cyclization sequence is described.

Abstract Disubstituted benzimidazoles are selectively obtained by reaction of o‐phenylenediamine (I) with various (hetero)aromatic and aliphatic aldehydes using trifluoroethanol or hexafluoro‐2‐propanol as solvent.

Abstract The total synthesis of the novel class antianginal drug ranolazine in its racemic (I) and enantiopure forms is described.

Abstract The catalytic potential of different fluoroboric acid‐derived catalyst systems is investigated for the cyclocondensation reaction α‐diketones (I), aldehydes (II) and ammonium salt to form trisubstituted imidazoles (III) as well four component using an additional amine (V) afford tetrasubstituted derivatives (VI).