Microwave-assisted preparation of cyclic ureas from diamines in the presence of ZnO

Exploring the untapped catalytic application of a ZnO/CuI/PPy nanocomposite for the green synthesis of biologically active 2,4,5-trisubstituted imidazole scaffolds

This work is focused on designing an innovative, efficient, and reusable heterogeneous ZnO/CuI/PPy nanocomposite via the self-assembly approach where pyrrole is oxidized into polypyrrole (PPy) and pyrrole also behaves as a reductant in the presence of KI. This so-obtained material was characterized by XRD, FTIR, FESEM, EDX, TEM, XPS, and ICP. TEM clearly shows a spherical morphology with the particle size ranging between 18 and 42 nm. The fabricated nanomaterial was tested for one-pot catalytic synthesis of biologically active 2,4,5-trisubstituted imidazoles under solvent-free conditions. The present work includes the benefits of an easy work-up procedure, higher product yield, shorter reaction duration, and no additional additive requirement under green and sustainable conditions. Moreover, the catalyst exhibited reusability for six runs with no considerable reduction in the respective yields and reactivity (confirmed by XRD, SEM, and TEM of the recycled catalyst). The ICP study shows very low leaching of copper (2.08 ppm) and zinc (0.12 ppm) metals. The approach also presented better values of green metrics like the E-factor, process mass intensity, carbon efficiency and reaction mass efficiency.

Application of Zinc Oxide to Obtain and Modify Properties of Adipate Plasticizer of Polyvinyl Chloride

Heterogeneous catalysts are widely used in basic research and in the petrochemical industry due to their effectiveness. In modern times, interest in this type of catalyst and, in particular, in mineral oxides is associated with the technological design of the process, namely: The absence of waste emissions, and the possibility of regeneration and reuse of the catalyst, which meets the criteria of green chemistry. For this reason, the preparation of non-toxic adipate plasticizers is expediently carried out under conditions of heterogeneous catalysis. Zinc oxide was chosen for this purpose, and as initial reagents: Adipic acid, butoxyethanol, and phenoxyethanol. For synthesized butoxyethylphenoxyethyl adipate by thermogravimetry on a TGA-DSC-combined thermal analysis instrument and differential scanning calorimetry on a DSC-1 instrument («Mettler Toledo»), the following properties were studied: Thermal stability, melting and crystallization temperatures, polymer compatibility. An analysis of the data in comparison with di-2-ethylhexylphthalate confirmed the possibility of using it as a plasticizing additive in PVC compositions. The zinc compound obtained in situ as part of the developed plasticizing composition contributes to increasing the color and thermal stability of the obtained PVC compositions.

Scaffolding-Induced Property Modulation of Chemical Space

Physicochemical property switching of chemical space is of great importance for optimization of compounds, for example, for biological activity. Cyclization is a key method to control 3D and other properties. A two-step approach, which involves a multicomponent reaction followed by cyclization, is reported to achieve the transition from basic moieties to charge neutral cyclic derivatives. A series of multisubstituted oxazolidinones, oxazinanones, and oxazepanones as well as their thio and sulfur derivatives are synthesized from readily available building blocks with mild conditions and high yields. Like a few other methods, MCR and cyclization allow for the collective transformation of a large chemical space into a related one with different properties.

A novel one-pot method for the stereoselective synthesis of tetrahydropyrimidinones in a low melting mixture

A direct and metal free one-pot method has been developed for the stereoselective synthesis of tetrahydropyrimidinone derivatives from a vinyl arene and formaldehyde using a tartaric acid-dimethylurea (TA : DMU) melt as a green reaction medium. The substrate scope of this method is very general and the tetrahydropyrimidinone (THPM) derivatives are synthesized in good yields with a high degree of diastereoselectivity. In this reaction, the melt plays a triple role as the solvent, catalyst and reagent.

Metal-Free Synthesis of N-(Carboselenoate) Benzimidazolones by Cascade Cyclization of ortho-Diisocyanoarenes and Selenosulfonates

A facile synthesis of N-(carboselenoate) benzimidazolones through metal-free reactions of ortho-diisocyanoarenes with selenosulfonates is reported here. The desired products are obtained in moderate to good yields with good functional group compatibility. The ortho-diisocyanoarenes are applied to the construction of 2-benzimidazolone derivatives for the first time.

1,3-Oxazinan-2-ones via carbonate chemistry: a facile, high yielding synthetic approach

A high yielding synthesis of 1,3-oxazinan-2-ones starting from 3-amino-1-propanols and ethylene carbonate (EC) in the presence of catalytic amount of triazabicyclodecene (TBD) is herein reported. The formation of six-membered cyclic carbonates was achieved by intermolecular cyclization reaction via double BAc2 mechanism. Cyclization reactions have been carried out in neat as EC acted both as solvent and reagent. Pure 1,3-oxazinan-2-ones were isolated in high yield by simple liquid-liquid extraction. Further purification can be achieved by recrystallization. The reaction resulted of general application on different substrates including an aryl bis(3-amino-proan-1-ol) compound.

Synthesis of ferrocene-containing six-membered cyclic ureas via α-ferrocenyl carbocations

A convenient method for the synthesis of ferrocene-containing six membered cyclic ureas was developed.

Microwave-assisted organic synthesis and transformations using benign reaction media

A nonclassical heating technique using microwaves, termed "Bunsen burner of the 21st century", is rapidly becoming popular and is dramatically reducing reaction times. The significant outcomes of microwave (MW)-assisted green chemistry endeavors, which have resulted in the development of synthetic protocols for drugs and fine chemicals synthesis that are relatively more sustainable, are summarized. The use of emerging microwave-assisted chemistry techniques in conjunction with greener reaction media is dramatically reducing chemical waste and reaction times in several organic syntheses and chemical transformations. A brief historic account of our own experiences in developing MW-assisted organic transformations, which involve various benign alternatives, such as solid-supported reagents, and greener reaction media, namely, aqueous, ionic liquid, and solvent-free, for the synthesis of various heterocycles, coupling reactions, oxidation-reduction reactions, and some name reactions are described. Synthesis of Heterocycles. The synthetic chemistry community has been under increased pressure to produce, in an environmentally benign fashion, the myriad of heterocyclic systems required by society in a short span of time, and one of the best options to accelerate these synthetic processes is to use MW technology. The efficient use of the MW heating approach for the synthesis of various heterocyclic compounds in aqueous and solvent-free medium is discussed. Organic Named Reactions. The application of MW chemistry for various named reaction such as the Prins reaction, the Suzuki reaction, the Heck reaction, the Aza-Michael reaction, Trost's gamma-addition, and the Cannizzaro reaction are summarized. Synthesis and Application of Ionic Liquids. Ionic liquids (ILs), being polar and ionic, in character couple with MW irradiation very efficiently and are, therefore, ideal MW-absorbing candidates for expediting chemical reactions. MW-assisted solvent-free synthesis and application of ILs are discussed. Oxidation-Reduction Reactions. MW protocols using mineral oxides such as alumina, silica, and clay to immobilize reagents on such solid supports have been extensively explored under "dry" media conditions. Various solvent-free examples of oxidation reactions are discussed that involve mixing of neat substrates with clay-supported iron(III) nitrate (clayfen) or iodobenzene diacetate (IBD) as an oxidant; some interesting MW reduction protocols using borohydrides are also discussed. Protection-Deprotection Reactions. The protection and deprotection of alcohols and amines are common events in multistep organic syntheses. Various protection and deprotection protocols under MW irradiation are discussed, including tetrahydropyranylation and (benzyloxycarbonyl) (Cbz)-protection, which are the most frequently employed methods.