Green Synthesis of 2-thioxothiazolidin-4-one Derivatives in Deep Eutectic Solvents via Knoevenagel Condensation

Recently, more and more researchers are resorting to green methods and techniques to avoid environmental pollution. Accordingly, many researchers have been working on the development of new green synthetic procedures trying to avoid the use of toxic organic solvents. A sustainable concept of green and environmentally friendly solvents in chemical synthesis nowadays encompasses a relatively new generation of solvents called deep eutectic solvents (DESs). DESs often have a dual role in the synthesis, acting as both, solvents and catalysts. In this study, DESs are used in the Knoevenagel synthesis of rhodanine derivatives, with no addition of conventional catalysts. A model reaction of rhodanine and salicylaldehyde was performed in 20 different DESs at 80 °C, in order to find the best solvent, which was further used for the synthesis of the series of desired compounds. A series of rhodanines was synthesized in choline chloride: acetamide (ChCl:acetamide) DES with good to excellent yields (51.4 – 99.7 %).

Substituent Effect on AIE Mechanism of Two Coumarin Derivatives: Uncommon TICT Fluorescence in Aggregation State

Two coumarin derivatives, 7-diethylamino-3-(4-nitrophenyl)coumarin (DNC) and 7-hydroxy-3-(4-nitrophenyl)coumarin (HNC), were synthesized via Knoevenagel condensation of salicylaldehyde derivatives with 4-nitrophenylacetonitrile and then cyclization reaction. Both of them were characterized by single-crystal X-ray diffraction. The molecules of DNC are stacked via π-π interaction, while the hydrogen bond interactions instead of π-π interaction were observed in the crystal packing of HNC. Both of DNC and HNC showed solvatochromic properties and aggregation-induced emission (AIE) activities, but the AIE characteristics of them were entirely different. HNC exhibited an AIE phenomenon as the result of the restriction of twisted intramolecular charge transfer (TICT), while DNC emited peculiar dual fluorescence which was assigned to the emission based on the inhibition of TICT state formation and the emission from the TICT state respectively.

Novel copolymers of styrene. 15. Halogen ring-disubstituted propyl 2-cyano-3-phenyl-2-propenoates

Novel halogen ring-disubstituted propyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2C3H7 (where R is 2-fluoro-5-methyl, 3-iodo-4-methoxy, 5-iodo-2-methoxy, 3,5-dichloro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 2-chloro-6-fluoro, 3-chloro-2-fluoro, and 3-chloro-4-fluoro) were prepared and copolymerized with styrene. The propenoates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-disubstituted benzaldehydes and propyl cyanoacetate, and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. All the propenoates were copolymerized with styrene (M1) in solution with radical initiation (ABCN) at 70C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C-NMR, GPC, DSC, and TGA. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200-500ºC range with residue (1-3% wt.), which then decomposed in the 500-800ºC range.

Novel copolymers of vinyl acetate. 4. Halogen ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates

Novel copolymers of vinyl acetate and halogen ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2C2H5 (where R is 2-Br, 3-Br, 4-Br, 2-Cl, 3-Cl, 4-Cl, 2-F, 3-F, 4-F, 2,3-dichloro, 2,4-dichloro, 2,6-dichloro, 3,4-dichloro, 2,4-difluoro, 2-bromo-3,4-dimethoxy) were prepared in solution with radical initiation at 70C. The propenoates were synthesized by the piperidine catalyzed Knoevenagel condensation of halogen ring-substituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Thermal behavior of the copolymers was studied by DSC (Tg) and TGA. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 159-500ºC range with residue (8.8-15.2 wt%), which then decomposed in the 500-650ºC range.

Novel copolymers of vinyl acetate. 3 Ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates

Novel copolymers of vinyl acetate and ring-substituted ethyl 2-cyano-3-phenyl-2-propenoates, RPhCH=C(CN)CO2C2H5 (where R is 4-acetoxy, 4-acetamido, 2-cyano, 3-cyano, 4-cyano, 4-dimethylamino, 4-diethylamino, 2,4,6-trimethyl, 2,3-dimethyl-4-methoxy, 2,4-dimethoxy-3-methyl were prepared in solution with radical initiation at 70C. The propenoates were synthesized by the piperidine catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and ethyl cyanoacetate, and characterized by CHN analysis, IR, 1H and 13C-NMR. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H and 13C-NMR. Thermal behavior of the copolymers was studied by DSC (Tg) and TGA. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 160-350ºC range with residue (1.5-15.1 wt%), which then decomposed in the 500-650ºC range.

Synthesis and Molecular Docking Studies of N,N-Dimethyl Arylpyranopyrimidinedione Derivatives

The synthesis of N,N-dimethyl arylpyranopyrimidinedione derivatives from aromatic aldehydes, N-methyl-1-(methylthio)-2-nitroethamine (NMSM) and 1,3-dimethyl barbituric acid, in the presence of piperidine as a catalyst, is reported. The reaction mechanism involves a Knoevenagel condensation, followed by Michael addition and intramolecular O-cyclization reaction sequence. The synthesized compounds were docked with human kinesin Eg5 protein to calculate binding energy, inhibition constant and H-bond interaction. All the compounds show good binding affinity towards the protein, with significant docking score.

Supported copper on a diamide–diacid-bridged PMO: an efficient hybrid catalyst for the cascade oxidation of benzyl alcohols/Knoevenagel condensation

In this study, a novel periodic mesoporous organosilica (PMO) containing diamide–diacid bridges was conveniently prepared using ethylenediaminetetraacetic dianhydride to support Cu(ii) species and affording Cu@EDTAD-PMO nanoparticles efficiently.

Knoevenagel Condensations Catalyzed by New Oil Shale Recyclable Catalyst at Room Temperature and Assisted by Ultrasounds Irradiations

Functionalized alkenes were successfully synthesized via a clean procedure in a short time by using a new recycled heterogeneous catalyst prepared from Moroccan oil shale, this catalyst is characterized by different technics such XRD, BET-BJH, MEB-EDS, and TGA, before it’s has been used in the Knoevenagel condensation between different aldehydes and active methylenes. The results showed that coupling the catalyst with ultrasound irradiations could improve the catalytic system in this transformation by achieving the products in a very short time, the results showed clearly that this catalyst could be considered as excellent recyclable support in Knoevenagel condensation.