Display omitted
•Highly efficient and recyclable homogeneous catalyst.•α-Amino acids and aromatic amines as donor-acceptor pairs.•Catalyst recovery and reuse up to 6 cycles.•Efficient for 8 types of ...nucleophiles.
An efficient and recyclable homogeneous catalyst is developed using commercially cheap l-proline and melamine for the synthesis of chromenes and spirochromenes (spirooxindoles) via multicomponent reactions at room temperature. Systematic studies were conducted in order to achieve desired reactivity and recyclability of the catalyst using various α-amino acids and aromatic amines as donor-acceptor pairs. Among the screened combinations, l-proline and melamine (3:1 ratio; 3mol% on total weight) was found to be best catalyst to give the desired products with excellent yields (up to 99%) in very short times (1–15min) at room temperature in DMSO as solvent. The catalyst was recovered by adding EtOAc and reused up to 5 cycles without losing the catalytic activity.
Herein, the direct α‐sulfenylation of a series of β‐dicarbonyl, β‐ketophosphonate, and β‐ketonitrile compounds, mediated by sulfonium salts has been described. Traditionally, sulfonium salts which ...are synthesized by activation of dialkylsulfoxides serve as oxidizing agents or precursors of sulfur ylide. In this transformation, sulfonium salts as readily prepared and operationally simple sulfenylation reagents firstly achieved alkylsulfenylation of various activated C(sp3)−H bonds with the formation of tetra‐substituted carbon center.
The direct alkylsulfenylation of various activated C−H bonds has been reported. The reaction utilizes sulfonium salts as sulfenylation reagents which are readily prepared, operationally simple, and performe under mild reaction conditions.
Display omitted
•Use of “On-water” concept for tetrahydrothiophene synthesis.•Catalyst-free protocol for the spiro-barbiturates.•Consecutive/one-pot sequence for Knoevenagel, thia-Michael and Aldol ...reactions.•Simple procedure for the all carbon quaternary cantered molecules.
A green and efficient method have been developed for the synthesis of quaternary centered and spiro-barbiturate-tetrahydrothiophene hybrids via Knoevenagel condensation,1,4-thia-Michael and intramolecular Aldol reactions using “on water” concept under catalyst-free conditions. Systematic studies were carried out to find the role of the water and total reaction concentration (0.086M) to promote the reaction in two steps (one-pot). The use of water as a reaction medium, catalyst-free conditions, broad substrate scope, one-pot approach for the creation of quaternary centered and spiro molecules are the advantages of this method.
A simple method for the direct activation of phenyl acetylenes (spC-H activation) and selective synthesis of 3-hydroxy-3-(indol-3-yl) indolin-2-ones and 3,3′-bis(indolyl)indolin-2-ones (via ...Friedel-Crafts alkylation reaction) is reported in presence of CuWO4 (10 mol%) nanoparticles in aqueous medium. The catalyst was regenerated and reused up to 6 cycles without losing catalytic activity. This is the first report for the spC-H activation using CuWO4 and enjoys broad substrate scope for both the reactions.
Display omitted
•Direct spC-H activation of phenyl acetylenes in aqueous medium.•First application of CuWO4 nanoparticles for organic transformation.•CuWO4 nanoparticles as recyclable heterogeneous catalyst.•Selective synthesis of 3-hydroxy-3-(indol-3-yl) indolin-2-one at room temperature.•Selective synthesis of unsymmetrical 3,3′-bis-(indolyl)indolin-2-ones.
Regioselectivity-switchable reactions hold irreplaceable importance in the construction of diversified architectures. In this work, Brønsted base-catalyzed regioselectivity-switchable annulations ...between alkynyl α-diketones and α-cyanoketones have been achieved for the first time, delivering a series of skeletally thoroughly different dihydrofurofuran and furan derivatives. A range of novel transformations of the products can be realized. The work also demonstrates the unique features of alkynyl α-diketone chemistry, which are in sharp contrast to the current understanding of ynone-related chemistry.
The first example of a retro-Henry type reaction is reported using 3-hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones which are prepared
via
catalyst-free Henry reaction of ...3,5-dimethyl-4-nitroisoxazole and isatin. These compounds were used for the selective synthesis of 3-hydroxy-indolyl-2-oxindoles and bis-indolyl-2-oxindoles (symmetric/unsymmetric)
via
retro-Henry type reaction followed by Friedel-Crafts alkylation reactions in water (one-pot approach). 3-Hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones on hydrolysis yielded 2-(3-hydroxy-2-oxoindolin-3-yl)acetic acids, which are sources of natural products and biologically active compounds.
The first example of a retro-Henry type reaction is reported using 3-hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones which are prepared
via
catalyst-free Henry reaction of 3,5-dimethyl-4-nitroisoxazole and isatin.
Functionalized dibenzo-1,4-diazepin-1-ones were synthesized using the “on-water” concept in the presence of l -proline (organocatalyst; 20 mol%) and under catalyst free conditions (sealed tube) in an ...aqueous medium. The resulting molecules were tested ( in vitro ) for α-glucosidase (isolated from Saccharomyces cerevisiae ) enzyme inhibition using acarbose as a standard drug (IC 50 32.47 ± 1.64). The enzyme inhibition kinetic analysis of selected molecules showed the competitive mode of inhibition (best result; IC 50 39.31 ± 1.68) against α-glucosidase. Molecular docking studies of these compounds with the MAL12 homology model showed HIS279A as a major interacting residue in the binding site of the protein which is a similar binding mode consistent with the binding of acarbose.
Reactors parts: 1) Syringe Pump 2) Syringe 3) Inlet &z.rtrif; 4) Stainless steel coil microreactor (SSCR–2mm, SSCR–1mm and Corning® AFR) 5) Outlet 6) Beaker for sample collecting.
Display omitted
•A ...continuous mode of 5-(4′-methyl-1,1′-biphenyl-2-yl)-1-trityl-1H-tetrazole MBPTT production has been successfully carried with differeent microreactors.•Better yield has been obtained with Corning® AFR reactor.•Reacton time has been reduced drastically, while compared with conventional batch mode reactor.
Currently, process intensification research is focused on use of the continuous micro reactor over the batch reactors. The micro reactor process gives continuous product output, effective micro mixing and better yield in small residence time over batch reactors. A continuous flow process has been successfully developed for the tritylation of 5-(4′-methyl-1,1′-biphenyl-2-yl)-1H-tetrazole MBPT using different microreactors. The reaction was carried out in three different configurations of microreactors. The SSCR–1mm and 2mm (Stainless steel capillary coil micro reactors) gives yield of 93.72 and 92.87% for the residence time of 71s and 324s respectively. Among the three microreactors, Corning® AFR afforded effectively higher yield (95.18%) for the residence time of 27s. Thus, 5-(4′-methyl-1,1′-biphenyl-2-yl)-1-trityl-1H-tetrazole, a useful intermediate material for some of the pharmaceutical products that can be produced industrially using microreactor.
