Recent advances in fixation of CO_(2) into organic carbamates through multicomponent reaction strategies

Carbon dioxide(CO_(2)) is the main greenhouse gas and also an ideal C1 feedstock in organic synthesis because it is abundant,nontoxic,nonflammable,and renewable.The synthesis of organic carbamates using CO_(2) as a phosgene alternative has attracted extensive attention because of the importance of carbamates in organic synthesis and in the pharmaceutical and agrochemical industries.In recent decades,many multicomponent reaction strategies have been designed for constructing different types of organic carbamate molecules.Most of these methods rely on the in situ generation of carbamate anions from CO_(2) and amines,followed by reactions with other coupling partners.Synthetic strategies for acyclic carbamates include nucleophile‐electrophile coupling,nucleo‐phile‐nucleophile oxidative coupling,difunctionalization of unsaturated hydrocarbons,and C–H bond functionalization.Strategies for the synthesizing cyclic carbamates include carboxylative cyclization of in situ‐generated unsaturated amines and difunctionalization of unsaturated amines with CO_(2) and other electrophilic reagents.This review summarizes the recent advances in the synthesis of organic carbamates from CO_(2) using different multicomponent reaction strategies.Future perspectives and challenges in the incorporation of CO_(2) into carbamates are also presented.

Multicomponent Reaction in Ionic Liquid: A Novel and Green Synthesis of 1, 4-Dihydropyridine Derivatives

An efficient and green method for the synthesis of 1, 4-dihydropyridine derivatives mediated in an ionic liquid, [bmim][BF4], through a four-component condensation process of aldehydes, 1, 3-dione, Meldrum＇s acid and ammonium acetate is disclosed in this paper.

Prediction of Multicomponent Reaction Yields Using Machine Learning

Prediction of reaction yields using machine learning(ML)can help chemists select high-yielding reactions and provide prior experience before wet-lab experimenting to improve efficiency.However,the exploration of a multicomponent organic reaction features many complex variables and limited number of experimental data,which are challenging for the application of ML.Herein,we perform yield prediction for the synthesis of 2-oxazolidones via Cu-catalyzed radical-type oxy-alkylation of allylamines and herteroaryl-methylamines with CO_(2),which is a three-component reaction.Using physicochemical descriptors as features to launch ML modelling,we find that XGBoost shows significantly improved performance over linear models and these features are effective for the yield prediction.Moreover,out-of-sample prediction indicates the application potential of the model.This study demonstrates great potential of regression-modelling-based ML in organic synthesis even with complex factors and a general small size of reaction data,which are generated from the classical research pattern of method for the inquiry of multicomponent reactions.

Pillar[5]arene-based [3]rotaxanes: Convenient construction via multicomponent reaction and pH responsive self-assembly in water

Four pillar[5]arene based[3]rotaxanes(1-4)involving two 1,4-diethoxypillar[5]arene(DEP5)rings and a dumbbell-shaped component were successfully synthesized.The dumbbell-shape molecules contain one longer bridge,two triazole sites and two multicomponent stoppers.After threading DEP5 rings with linear guests(G1-G4)which contain two benzaldehyde units,the base catalyzed three-component reaction of dimedone,malononitrile and benzaldehyde was performed to construct the stoppers and connected the pseudorotaxanes with stoppers to generate 1-4.The structures of[3]rotaxanes and their self-assembly behaviors were characterized by 1 H NMR,13C NMR,NOESY,HR-ESI-MS,DLS and TEM technologies.We hope that pillar[5]arene based[3]rotaxanes may have potential applications in drug delivery systems and molecular devices.

Two tandem multicomponent reactions for the synthesis of sequence-defined polymers

Multicomponent polymerizations have become powerful tools for the construction of sequence-defined polymers. Although the Passerini multicomponent reaction has been widely used in the synthesis of sequence-defined polymers, the tandem usage of the Passerini multicomponent reaction and other multicomponent reactions in one-pot for the synthesis of sequence-defined polymers has not been developed until now. In this contribution, we report the tandem usage of the Passerini three-component reaction and the three-component amine-thiol-ene conjugation reaction in one pot for the synthesis of sequence-defined polymers. The Passerini reaction between methacrylic acid, adipaldehyde, and 2-isocyanobutanoate was carried out, affording a new molecule containing two alkene units. Subsequently, an amine and a thiolactone were added to the reaction system, whereupon the three-component amine-thiol-ene conjugating reaction occurred to yield a sequence-defined polymer. This method offers more rapid access to sequence-defined polymers with high molecular diversity and complexity.

An Environmentally Benign Catalytic Method for Versatile Synthesis of 1,4-Dihydropyridines via Multicomponent Reactions

The synthesis of diverse 1,4-dihydropyridines have been achieved via the multicomponent reactions of aldehydes,enaminones and amines.The reactions have been smoothly performed in water to provide all products with moderate to excellent yields by using lactic acid as a green catalyst.

Sustainable functionalization and modification of materials via multicomponent reactions in water

In materials chemistry,green chemistry has established firm ground providing essential design criteria to develop advanced tools for efficient functionalization and modification of materials.Particularly,the combination of multicomponent reactions in water and aqueous media with materials chemistry unlocks a new sustainable way for constructing multi-functionalized structures with unique features,playing significant roles in the plethora of applications.Multicomponent reactions have received significant consideration from the community of material chemistry because of their great efficiency,simple operations,intrinsic molecular diversity,and an atom and a pot economy.Also,by rational design of multicomponent reactions in water and aqueous media,the performance of some multicomponent reactions could be enhanced by the contributing“natural”form of water-soluble materials,the exclusive solvating features of water,and simple separating and recovering materials.To date,there is no exclusive review to report the sustainable functionalization and modification of materials in water.This critical review highlights the utility of various kinds of multicomponent reactions in water and aqueous media as green methods for functionalization and modification of siliceous,magnetic,and carbonaceous materials,oligosaccharides,polysaccharides,peptides,proteins,and synthetic polymers.The detailed discussion of synthetic procedures,properties,and related applicability of each functionalized/modified material is fully deliberated in this review.

Multicomponent Reactions for Diverse Synthesis of N-Substituted and NH 1,4-Dihydropyridines

The multicomponent reactions of aldehydes,electron deficient alkynes and amines have been successfully per-formed to yield a number of symmetrical 2,6-unsubstituted 1,4-dihydropyridines(1,4-DHPs).This method has been found generally applicable for the synthesis of both N-substituted and N-unsubstituted 1,4-DHPs by employing secondary amine to activate the alkyne component via enaminoester intermediates.The present method runs through an enamine type activation,which is different from the known approach employing AcOH as solvent.

Multifunctional Polymer-Protein Conjugates Generated by Multicomponent Reactions

Recently,multifunctional polymers for protein conjugation have been facilely synthesized through the multicomponent reactions(MCRs).In this mini-review,current progress in the generation of multifuncti onal polymers with protei n-reactive groups via MCRs is summarized.These mult functional polymers react with model therapeutic proteins,forming multifunctional polymer-protein conjugates,which are prototypes of sophisticated theranostic agents and antibacterial vaccine candidates.In comparison with the traditional multi-step synthesis,the preparation of multifunctional polymers for protein conjugation through MCRs is straightforward and convenient.Due to these properties,MCRs have the potential to become a new general strategy to achieve polymer-protein conjugates for biological and medical applications.

Bismuth (III) Triflate Catalyzed Multicomponent Synthesis of 2,4,5-Trisubstituted Imidazoles

Substituted imidazoles are of interest because of their useful biological activities. While several methods have been developed for the synthesis of such compounds, some of the reported methods utilize corrosive or toxic catalysts. We report a bismuth (III) triflate catalyzed multicomponent synthesis of 2,4,5-trisubstituted imidazoles. Bismuth (III) compounds are attractive from a green chemistry perspective because they are remarkably non-toxic and non-corrosive. Multicomponent syntheses save time and generate less waste.

Bismuth (III) Triflate Catalyzed Multicomponent Synthesis of 2,4,5-Trisubstituted Imidazoles

Substituted imidazoles are of interest because of their useful biological activities. While several methods have been developed for the synthesis of such compounds, some of the reported methods utilize corrosive or toxic catalysts. We report a bismuth (III) triflate catalyzed multicomponent synthesis of 2,4,5-trisubstituted imidazoles. Bismuth (III) compounds are attractive from a green chemistry perspective because they are remarkably non-toxic and non-corrosive. Multicomponent syntheses save time and generate less waste.

AN ENGINEERING MODEL FOR MULTICOMPONENT REVERSIBLE REACTION NETWORK

The treatment of a multicomponent reversible reaction network is extremely complicated because largenumber of rate constants must be precisely determined and because the calculation based on these rateconstants is tedious.In order to reduce the degrees of freedom of the process,the authors propose a methodin which the reactor and the separator are regarded as a whole.Based on this approach,an N-componentreversible reaction system can be dealt with as a two—component system.Consequently,a simple and ac-cessible way of the apparent rate determination is suggested.For fiist-order reactions,an explicit,simplifiedexpression has been derived for both lumped and distributed parameter reaction systems.

Switchable Multicomponent Cyclization Reactions to Access Fluoroalkylated Dihydropyrimidines and Pyrimidines under Solvent-Free Conditions

Comprehensive Summary The development of switchable solvent-free multicomponent reactions to build high-value-added products is an important demand for organic synthesis.Herein,we detailed the successful implementation of a switchable strategy for the construction of diverse 4-fluoroalkyl-1,4-dihydropyrimidines and 4-fluoroalkyl-pyrimidines via a solvent/additive-free[3+2+1]annulation,starting from readily available enamines,trifluoroacetaldehyde hydrate or 1-ethoxy-2,2-difluoroethanol and amidines hydrochloride.This reaction conforms to the concept of green synthesis,and provides a new avenue to access valuable fluorinated heterocycles.

Three-component Reaction of Aromatic Aldehyde,Malononitrile and Aliphatic Amine Leading to Different Pyridine Derivatives

The three-component reaction of aromatic aldehyde,malononitrile and aliphatic amine in a mixed solvent of methanol and water exhibited very interesting molecular diversity and gave the derivatives of polysubstituted N-methyldihydropyridines,2-dialkylaminopyridines and 2-methoxypyridines as main products according to the structure of aliphatic amines used.

Synthesis of 2,4-Diarylcyclooctenopyridines with One-pot Four-component Reactions

An efficient one-pot four-component reaction has been developed for the synthesis of 2,4-diarylcyclooctenopyridines, in moderate yields. This route is an effective modified two-step synthesis of Krohnke pyridine and involves a four-component tandem reaction of pyridinium bromide with aromatic aldehydes and cyclooctanone in a system of NHaOAc/HOAc under microwave irradiation.

Bismuth (III) Chloride Catalyzed Multicomponent Synthesis of Substituted Hexahydroimidazo[1, 2-<i>a</i>]Pyridines

The synthesis of nitrogen containing heterocycles is of particular interest in the pharmaceutical industry due to the range of biological activities exhibited by such compounds. Their synthesis using multicomponent reactions saves steps and minimizes waste generation. The bismuth (III) chloride multicomponent synthesis of a series of hexahydroimidazo[1, 2-a]pyridines is reported. Bismuth (III) compounds are especially attractive from a green chemistry perspective because they are remarkably nontoxic, non-corrosive and relatively inexpensive. The reported method avoids chromatography and an aqueous waste stream to afford the products in a very mass efficient manner.

Electrochemical Multicomponent Cascade Radical Process Enabling Synthesis of lodomethyl Spiropyrrolidinyl-Oxindoles

A novel electrochemical multicomponent cascade reaction of indole-tethered alkenes with CF_(3)SO_(2)Na and n-BuaNI has been developed,which enables the rapid assembly of spiropyrrolidinyl-oxindoles in good yields.The experimental results and DFT calculations suggest that this reaction proceeds through the oxidation of CF_(3)SO_(2)Na,radical coupling with alkene,spirocyclization,oxidation of sulfinate,iodide substitution,and water coupling.This strategy features mild reaction conditions,easy-to-handle reactants,and good chemical yields.This finding not only enriches the research contents of indole-tethered alkenes but also provides a green strategy for the construction of spiropyrrolidinyl-oxindoles compared with the existing methodologies.

Silica supported perchloric acid(HClO_4-SiO_2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of amidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.

Sulphamic Acid （H2NSO3H）-Catalyzed Multicomponent Reaction of β-Naphthol： An Expeditious Synthesis of Amidoalkyl Naphthols

Sulphamic acid （H2NSO3H） was found to be an efficient catalyst for the multicomponent condensation reaction of β-naphthol, aromatic aldehydes and urea or amides to afford the corresponding α-amidoalkyl-β-naphthols in good yields. The remarkable features of this new procedure are high conversions, short reaction time, clean reaction profiles and simple experimental and work-up procedures.

Numerical simulation of micromixing effect on the reactive flow in a co-rotating twin screw extruder

To control the multicomponent reactions in extrusion, reactive-mixing flow in a co-rotating twin screw extruder was numerically studied in the present paper. Effects of initial species distribution, rotating speed and flow rate on a competitive-parallel reaction were investigated and the relationship between mixing and reactions was discussed from the view of chemical reaction engineering. The simulation results show the studied operational parameters, which determine residence time distribution, earliness of mixing and segregation degree of reactive-mixing flows, affect the local species concentration and reaction time and hence have significant influences on the reaction extent. Orthogonal test was adopted to clarify the significance of operational parameters.The analysis shows that initial species distribution and flow rate are the most important factors in the control of reaction extent, and effect of rotating speed is conditional depending on the micro-mixing status of the fluid.