The glycosylation of O-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of O-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding O-glycosides in moderate to good yields with predictable selectivity. In addition, the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor.

An efficient and operationally simple gold­(III)-catalyzed glycosylation protocol was developed using newly synthesized benchtop stable phenylpropiolate glycosyl (PPG) donors. Gold­(III)-catalyzed activation of PPGs proceeds well with various carbohydrate and noncarbohydrate-based glycosyl acceptors and leads to their corresponding O/N-glycosides in good to excellent yields with regeneration of reusable and easily separable phenylpropiolic acid. Differentially protected PPGs reacted well under the optimized reaction conditions. In particular, good anomeric selectivity was observed with mannosyl and rhamnosyl PPG donors. A preliminary mechanistic study reveals that the presence of a triple bond adjacent to the ester group is essential for activation, and PPG-based donor shows higher reactivity than analogous acetate and benzoate donors.

An efficient and regioselective palladium(II)-catalyzed primary acetamide assisted ortho arylation of arylacetamide has been discovered. This is the first report where functionalizable primary acetamide (-CHCONH) is used as a directing group for C(sp)-H activation/cross-coupling reactions, circumventing the extra steps of installation and subsequent removal of the directing groups. The synthetic utility of this transformation is demonstrated through the scale-up synthesis. In addition, the primary acetamide can be manipulated into synthetically important derivatives such as nitriles and carboxylic acids.

This review highlights the recent application of imidates as building blocks for the synthesis of saturated and un-saturated N-heterocycles via C–N annulation reactions under acid/base/metal-catalyzed/radical-mediated reaction conditions.

Process intensification aims at reducing the size of equipment by orders of magnitude and is actively perused in separation processes. Its feasibility in Pressure Swing Adsorption (PSA) processes has been explored. A 4-bed PSA and a 3-bed PSA, which emulate the moving bed processes, and duplex PSA and a modified duplex PSA have been selected for the exploratory studies. Simulation studies on the separation of a mixture of CH 4 -CO 2 over 5A zeolite were carried out to compare the performance of these processes. An index has been proposed to quantify the process intensification. The 3-bed PSA and the modified duplex PSA exhibited superior performance compared to the other two for a purity of 99.9 mol% of both the products. However, the performances of the processes other than duplex were comparable when purities were set at 95 mol%. In 3-bed PSA a modest process intensification of four times reduction in size and two times reduction in energy requirement appears to be feasible if benchmarked against the PSA based on the variant of the Skarstrom cycle. Notations bLangmuir parameter (m 3 /mol) c Concentration in gas phase (mol/m 3 ) C A Particle diameter (mm) D Diameter of bed (mm) D L0 Dispersion coefficient (m 2 /s) D M Molecular diffusivity (m 2 /s) E Energy (kJ/mol·feed) f Friction factor g c Gravitational constant (m/s 2 ) I P I , I P I Index for process intensification (thousand US $/y·(mol/s)) k i Linear driving force constant (s −1 ) L Bed length (m) L e Equivalent length of the valve (m) n Number of moles N Number of components P Pressure (bar) P Productivity of CH 4 (LSTP/h·kg of adsorbent) P H Adsorption pressure (bar) P I Intermediate desorption pressure (bar) P L Desorption pressure (bar) P 1 , P 2 Pressures used in (9) (bar) q Amount adsorbed in solid phase (mol/m 3 ) q e Amount adsorbed in solid phase at equilibrium with gas phase (mol/m 3 ) q s Saturation constant (mol/m 3 ) Q T Total amount adsorbed in solid phase (mol/m 3 ) R Universal Gas constant (bar·m 3 /mol·K) 122 Adsorption (2011) 17: 121-133