Materials Functionalization with Multicomponent Reactions: State of the Art

The emergence of neoteric synthetic routes for materials functionalization is an interesting phenomenon in materials chemistry. In particular, the union of materials chemistry with multicomponent reactions (MCRs) opens a new avenue leading to the realm of highly innovative functionalized architectures with unique features. MCRs have recently been recognized as considerable part of the synthetic chemist's toolbox due to their great efficiency, inherent molecular diversity, atom and pot economy along with operational simplicity. Also, MCRs can improve E-factor and mass intensity as important green chemistry metrics. By rational tuning of the materials, as well as the MCRs, wide ranges of functionalized materials can be produced with tailorable properties that can play important roles in the plethora of applications. To date, there has not reported any exclusive review of a materials functionalization with MCRs. This critical review highlights the state-of-the-art on the one-pot functionalization of carbonaceous and siliceous materials, polysaccharides, proteins, enzymes, synthetic polymers, etc., via diverse kind of MCRs like Ugi, Passerini, Petasis, Khabachnik-Fields, Biginelli, and MALI reactions through covalent or noncovalent manners. Besides the complementary discussion of synthetic routes, superior properties and detailed applicability of each functionalized material in modern technologies are discussed. Our outlook also emphasizes future strategies for this unprecedented area and their use as materials for industrial implementation. With no doubt, MCRs-functionalization of materials bridges the gap between materials science domain and applied chemistry.

Preparation and characterization of sulfonated poly(arylene thioether sulfone)/imino-containing phosphorylated silica particle composite proton exchange membranes

In this article, novel nanocomposite proton exchange membranes (PEMs) were prepared by embedding imino-containing phosphorylated silica nanoparticles into a sulfonated poly(arylene thioether sulfone) (SPTES) polymer matrix. SPTES was synthesized via condensation polymerization of 4,4′-thiobisbenzenethiol, 4,4′-difluorodiphenylsulfone, and disodium 3,3′-disulfonate-4,4′-difluorodiphenylsulfone. The imino-containing phosphorylated silica particles (Si-imP) were prepared by the Kabachnik–Fields reaction, which is confirmed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy. The results showed that the Si-imP were uniformly distributed in the composite membrane. The properties of the composite membranes, including thermal stability, water uptake, swelling ratio, oxidative stability, and proton conductivity, were thoroughly evaluated. Experimental results indicated that Si-imP may be effective reinforcement materials for SPTES membranes. It is noteworthy that an increase in proton conductivity from 0.138 S cm−1 of the SPTES control membrane to 0.173 S cm−1 of the composite membrane was achieved at the Si-imP content of 5 wt% under fully hydrated conditions at 80°C. This finding primarily stems from the fact that the Si-imP could be linked with the sulfonate ion clusters of SPTES to form more continuous ionic networks. These networks act as efficient proton-hopping pathways to enhanced proton conductivity. The nanocomposite membranes are demonstrated to be promising candidates as new polymeric electrolyte materials for PEM fuel cells operated at medium temperatures.

Functionalization of α-hydroxyphosphonates as a convenient route to N-tosyl-α-aminophosphonates

Direct conversion of the α-hydroxyl group by para-toluenesulfonamide to yield α-(N-tosyl)aminophosphonates is reported. α-Aminophosphonates 23a,b-37a,b were obtained from the corresponding α-hydroxyphosphonates 6a,b-21a,b in the presence of K2CO3, via the retro-Abramov reaction of the appropriate aldehydes, 1-5. The subsequent formation of imines with simultaneous addition of diethyl phosphite provided access to the α-sulfonamide phosphonates 23a,b-37a,b with better diastereoselectivity than in the case of the Pudovik reaction. The mechanism for this transformation is proposed herein. When Cbz N-protected aziridine 9a,b and phenylalanine analogue 12a,b were exploited, intramolecular substitution was observed, leading to the corresponding epoxide 38 as the sole product, or oxazolidin-2-one 39 as a minor product. Analogous substitution was not observed in the case of proline 18a,b and serine 21a,b derivatives.

The synthesis of HMF-based α-amino phosphonatesviaone-pot Kabachnik–Fields reaction

The first use of biomass-derived HMF in the one-pot Kabachnik–Fields reaction is reported here. A wide range of furan-based α-amino phosphonates were prepared in moderate to excellent yields under mild, effective and environmentally-benign conditions: iodine as a non-metal catalyst, biobased 2-MeTHF as the solvent and room or moderate temperature. The hydroxymethyl group of HMF persists in the Kabachnik–Fields products, widening the scope of further modification and derivatization compared to those arising from furfural. Issues involving the diastereoselectivity and double Kabachnik–Fields condensation were also faced.

A mild and efficient one-pot protocol for the synthesis of α-amino phosphonates directly from 5-HMF was described.

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

A family of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism was evaluated by DFT calculations. Two α-aminophosphonates were subjected to an X-ray study revealing a racemic dimer formation made through a N-H···O=P intermolecular hydrogen bridges pair.

Marrying multicomponent reactions and aggregation-induced emission (AIE): new directions for fluorescent nanoprobes

Recent development and progress for fabrication and applications of aggregation-induced emission polymers through multicomponent reactions have been summarized in this review.

Monoaminophosphorylated pillar[5]arenes as hosts for alkaneamines

New synthesized aminophosphonated pillar[5]arenes form host–guest complexes with aliphatic amines contrary to monoamine macrocycles that tend to self-assemble.

Synthesis of α-amino-lipophosphonates as cationic lipids or co-lipids for DNA transfection in dendritic cells

Cationic lipid/co-lipid combinations have been extensively explored in gene delivery as alternatives to viral vectors.

Sn(ii)-Mediated facile approach for the synthesis of 2-aryl-2H-indazole-3-phosphonates and their anticancer activities

The efficient synthesis of 2-aryl-2H-indazole-3-phosphonates has been achieved successfully via a SnCl₂·2H₂O mediated one-pot method.

One-pot synthesis of α-aminophosphonates via a cascade sequence of allylamine isomerization/hydrophosphonylation

A Rh/Ni-catalyzed cascade sequence of allylamine isomerization and hydrophosphonylation to synthesize α-aminophosphonates has been disclosed.

Stereoselective Synthesis of α-Amino-C-phosphinic Acids and Derivatives

α-Amino-C-phosphinic acids and derivatives are an important group of compounds of synthetic and medicinal interest and particular attention has been dedicated to their stereoselective synthesis in recent years. Among these, phosphinic pseudopeptides have acquired pharmacological importance in influencing physiologic and pathologic processes, primarily acting as inhibitors for proteolytic enzymes where molecular stereochemistry has proven to be critical. This review summarizes the latest developments in the asymmetric synthesis of acyclic and phosphacyclic α-amino-C-phosphinic acids and derivatives, following in the first case an order according to the strategy used, whereas for cyclic compounds the nitrogen embedding in the heterocyclic core is considered. In addition selected examples of pharmacological implications of title compounds are also disclosed.

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

Multicomponent reactions (MCRs) are one of the most important processes for the preparation of highly functionalized organic compounds in modern synthetic chemistry. As shown in this review, they play an important role in organophosphorus chemistry where phosphorus reagents are used as substrates for the synthesis of a wide range of phosphorylated heterocycles. In this article, an overview about multicomponent reactions used for the synthesis of heterocyclic compounds bearing a phosphonate group on the ring is given.

The Effect of New Thiophene-Derived Aminophosphonic Derivatives on Growth of Terrestrial Plants: A Seedling Emergence and Growth Test

The aim of this work was to synthesize selected thiophene-derived aminophosphonic systems and evaluate the phytotoxicity of newly obtained products according to the OECD 208 Guideline. Seven new thiophene-derived N-substituted dimethyl aminomethylphosphonic acid esters 2a–h were synthesized by the addition of an appropriate phosphite to azomethine bond of starting Schiff bases 1a–h, and NMR spectroscopic properties of aminophosphonates were investigated. These eight compounds were analyzed in regard to their phytotoxicity towards two plants, radish (Raphanus sativus) and oat (Avena sativa). On the basis of the obtained results, it was found that tested aminophosphonates 2a–h showed an ecotoxicological impact against selected plants, albeit to various degrees.

Cellular behavior of L929 and MG-63 cells cultured on electrospun nanofibers of chitosan with different degrees of phosphorylation

Phosphate groups chemically grafted onto polymer substrates can be used as biomimetic analogs for in vitro studying of function of biomacromolecules and also as tissue substitutes in clinical conditions of organ loss. Despite this inspiration, studies correlating effect of degree of phosphate grafting of a polymer on fabrication and biological properties of polymers are lacking. In this work, N-methylene phosphonic chitosan (PC) with different degrees of phosphate contents were synthesized and the effect of phosphate grafting on electrospinning behavior of substituted polymers is investigated. In PC, higher phosphate content widened concentration range for nanofiber formation. Balance between conductivity and viscosity of solutions played a determinant role in the success of electrospinning process. Culture of L929 cells showed grafting-dependent increase in cell proliferation. On the other hand, culture of MG-63 cells showed a positive correlation between grafting degree and Alkaline Phosphatase (ALP) expression. It is concluded that improvement of cell response parameters of nanofiber scaffolds can be attained as a function of controlled degree of phosphate grafting in polymeric biomaterials with implications for bone tissue engineering applications. Such studies may also be useful to develop quantitative structure activity relationships of functional polymers.

Design, Synthesis, and Antiviral Activity of Novel Ribonucleosides of 1,2,3-Triazolylbenzyl-aminophosphonates

A novel series of ribonucleosides of 1,2,3-triazolylbenzyl-aminophosphonates was synthesized through the Kabachnik-Fields reaction using I2 as catalyst followed by copper-catalyzed cycloaddition of the azide-alkyne reaction (CuAAC). All structures of the newly prepared compounds were characterized by (1) H NMR, (13) C NMR, and HRMS spectra. The structures of 2e, 2f, 3d, and 3g were further confirmed by X-ray diffraction analysis. These compounds were tested against various strains of DNA and RNA viruses; compounds 4b and 4c showed a modest inhibitory activity against respiratory syncytial virus (RSV) and compound 4h displayed modest inhibitory activity against Coxsackie virus B4.

C-H hydroxylation of phosphonates with oxygen in [bmIm]OH To produce quaternary α-hydroxy phosphonates

A highly efficient and mild [bmIm]OH-catalyzed α-hydroxylation of phosphonates using O2 as the oxygen source is described. The employment of ionic liquid under mild reaction conditions makes this transformation green and practical. Especially, this reaction provided a novel and convenient methodology for the construction of quaternary α-hydroxy phosphonates.

The catalytic aerobic synthesis of quaternary α-hydroxy phosphonates via direct hydroxylation of phosphonate compounds

A highly efficient Cu-catalyzed direct hydroxylation of phosphonate compounds has been developed. This transformation provides a powerful method for the synthesis of quaternary α-hydroxy phosphonates in good yields.

Crystal structure of diethyl [(4-nitrophenylamino)(2-hydroxyphenyl)methyl]phosphonate methanol monosolvate

In the title compound, C₁₇H₂₁N₂O₆P·CH₃OH, the planes of the 4-nitro­aniline and 2-hy­droxy­phenyl groups form a dihedral angle of 84.04 (8)°. The P atom exhibits tetra­hedral geometry involving two O-ethyl groups, a Cα atom and a double-bonded O atom. In the crystal, O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the α-amino­phospho­nic acid and methanol mol­ecules into chains that propagate parallel to the a axis.