The catalytic application of room temperature ionic liquids (RTILs) has been explored to catalyse the reaction of indole with aldehydes to afford bis(indolyl)methanes. The catalytic efficiency of the RTILs derived from butylmethylimidazolium (bmim) cation is influenced by the structure of the imidazolium moiety and the counter anion following the order:] decreased the catalytic efficiency. In the 1-methyl-3-alkylimidazolium methyl sulfates, the best results are obtained with the 3-butyl derivative and the catalytic property was retained with ethyl, n-propyl, and n-pentyl groups at N-3 although to a lesser extent with respect to the 3-butyl analogue. However, much reduction of the catalytic effect is observed with n-hexyl at N-3. The method is simple, environment friendly, compatible with various functional groups such as halogen, alkoxy, nitrile and O-t-Boc and gives excellent yields in short times. The catalyst is recyclable upto three consecutive uses. A mechanism has been proposed invoking ambiphilic dual activation role of the IL through the formation of intermediates involving hydrogen bond formation between the oxygen atom of the aldehyde carbonyl (or the transiently formed indolyl methanol in the subsequent step) and the C-2 hydrogen atom of the bmim cation, electrostatic intercation between the quarternary nitrogen atom of the bmim cation with the nitrogen lone pair of electrons of the indole and enforced hydrogen bond formation between the indole N-H hydrogen atom and the anion of the IL. The transient indolyl methanol and intermediate non-covalent clusters were "fished" by MALDI-TOF-TOF MS and MS/MS studies and served as 'proof-of-concept' to the mechanistic model.

Hydrogen-bond-driven electrophilic activation for selectivity control during competitive formation of 1,2-disubstituted and 2-substituted benzimidazoles from o-phenylenediamine and aldehydes is reported. The fluorous alcohols trifluoroethanol and hexafluoro-2-propanol efficiently promote the cyclocondensation of o-phenylenediamine with aldehydes to afford selectively the 1,2-disubstituted benzimidazoles at rt in short times. A mechanistic insight is invoked by NMR, mass spectrometry, and chemical studies to rationalize the selectivity. The ability of the fluorous alcohols in promoting the reaction and controlling the selectivity can be envisaged from their better hydrogen bond donor (HBD) abilities compared to that of the other organic solvents as well as of water. Due to the better HBD values, the fluorous alcohols efficiently promote the initial bisimine formation by electrophilic activation of the aldehyde carbonyl. Subsequently the hydrogen-bond-mediated activation of the in situ-formed bisimine triggers the rearrangement via 1,3-hydride shift to form the 1,2-disubstituted benzimidazoles.

Simple, convenient, and green synthetic protocols have been developed for the one pot synthesis of 2,3-disubstituted quinazolin-4(3H)-ones and 2-styryl-3-substituted quinazolin-4(3H)-ones under catalyst and solvent free conditions.

α-Ketoamides and their derivatives are key constituents of natural products, biologically relevant molecules, drug and drug candidates, and functional materials. Further, they are versatile and valuable intermediates and synthons in a number of functional group transformations and total syntheses. In recent years tremendous growth has been realized in the development of synthetic methods for α-ketoamide preparation and their applications in synthetic and medicinal chemistry. Among the various catalytic methods of α-ketoamide formation, two approaches, namely double aminocarbonylation and oxidative amidation, have received much more attention and have been greatly studied because of the ready availability of the starting materials, use of carbon monoxide (CO) as a direct source of carbonyl functionalities, and use of molecular oxygen (O2) or air as a green terminal oxidant and/or reactants. Catalyzed α-ketoamide formation can be roughly classified into metal- and nonmetal-catalyzed processes. In the context of metal catalysis, most reactions involving metals are performed using palladium (Pd) and copper (Cu); however, other metals such as gold (Au), silver (Ag), and iron (Fe) based catalysts have also been investigated to some extent. On the other hand, nonmetal-catalyzed α-ketoamide syntheses are mainly restricted to iodine-based catalysts in the presence or absence of other promoters. Our objective in this review is to highlight the important research endeavors related to catalytic α-ketoamide synthesis, which include the trends in the catalytic synthesis of α-ketoamides, new breakthroughs, and recent advances up to March 2016.

A novel strategy of catalytic green aerobic oxidation by surfactant-mediated oxygen reuptake in water offers a new dimension to the applications of surfactants to look beyond as solubility aids and a conceptual advancement in understanding the role of surfactants in aquatic organic reactions through mass spectrometry guided identification of discrete intermediates.