Thiourea isosteres as anion receptors and transmembrane transporters

Discovery of orally bioavailable inhibitors of MALT1 with in vivo activity for psoriasis

We report the design, synthesis, and biological activity of a series of compounds that exhibit potent mucosa-associated lymphoid tissue lymphoma translocation 1 (MALT1) inhibition. Structural transformation of the substructures of a starting compound gave amidomethyl derivatives and sulfonylguanidine derivatives that exhibited potent inhibition of MALT1. Compound 37 had good oral bioavailability and showed anti-psoriatic activity in an imiquimod-induced psoriasis mouse model after oral administration.

Recent advances in urea- and thiourea-containing compounds: focus on innovative approaches in medicinal chemistry and organic synthesis

Urea and thiourea represent privileged structures in medicinal chemistry. Indeed, these moieties constitute a common framework of a variety of drugs and bioactive compounds endowed with a broad range of therapeutic and pharmacological properties. Herein, we provide an overview of the state-of-the-art of urea and thiourea-containing pharmaceuticals. We also review the diverse approaches pursued for (thio)urea bioisosteric replacements in medicinal chemistry applications. Finally, representative examples of recent advances in the synthesis of urea- and thiourea-based compounds by enabling chemical tools are discussed.

Diaminomethylenemalononitriles and Diaminomethyleneindanediones as Dual Hydrogen Bond Donors for Anion Recognition

Diaminomethylenemalononitriles (DMMs) and diaminomethyleneindanediones (DMIs) are dual H-bond donors that have previously been used as organocatalysts, but their anion binding ability has not been investigated. We report the synthesis of both alkyl- and aryl-substituted DMMs and DMIs, together with a comparison of their anion binding ability with that of the analogous thioureas. The DMMs display affinity for monovalent anions, with similar anion binding affinities observed to that of the thioureas in acetonitrile, albeit with differing trends for the N,N'-dialkyl versus N,N'-diaryl compounds. In contrast, the DMIs do not bind to monovalent anions under similar conditions as a result of conformational locking through the formation of intramolecular H-bonds. This can be overcome upon addition of sulfate ions, and binding of sulfate is enhanced in a more competitive solvent (DMSO).

Biological applications of synthetic anion transporters

Transmembrane transport of anions by small molecules has recently been used to reduce the viability of cancer cells and fight against antibiotic-resistant and clinically relevant bacterial strains.

Synthesis of Cyclic Guanidines Bearing N-Arylsulfonyl and N-Cyano Protecting Groups via Pd-Catalyzed Alkene Carboamination Reactions

Palladium-catalyzed carboamination reactions of N-allylguanidines bearing cleavable N-cyano or N-arylsulfonyl protecting groups are described. The reactions afford cyclic guanidine products in good yield, and transformations of substrates bearing internal alkenes proceed with high diastereoselectivity. Deuterium labeling studies indicate these transformations proceed via anti-aminopalladation pathways.

A preorganized dual H-bond donor promotes benzoic acid active in the polymerization of δ-valerolactone

An enzyme-mimetic model follows squalene hopene cyclase is success in catalysis of ROP of δ-valerolactone in solution at room temperature by a carboxylic “strong” acid.

Beryllium-based fluorenes as efficient anion sponges

The F⁻, Cl⁻, CN⁻, NO₂⁻, NO₃⁻, and SO₄²⁻ anion affinities of 4,5-bis(BeX)-fluorene (X = H, F, Cl, CN, NC, and OCH₃) derivatives have been calculated at the B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) level of theory.

Convenient Synthesis of Unsymmetrical N,N′-disubstituted Thioureas in Water

A simple and convenient two-step method has been developed and used to synthesise 25 (4 of which are novel) unsymmetrical N,N′-disubstituted thioureas in water. Alkylamines or variously substituted arylamines reacted smoothly with phenyl chlorothionoformate at room temperature to form thiocarbamates, which were then reacted with another alkyl- or arylamine in water at reflux to afford the unsymmetrical N,N′-disubstituted thioureas in good to excellent yields. Mild conditions, simple work-up, high yields as well as using water as solvent are the major advantages of the method.

Internal Lewis pair enhanced H-bond donor: boronate-urea and tertiary amine co-catalysis in ring-opening polymerization

A new protocol of internal Lewis pair enhanced H-bond (LPHBD) catalysis for ring opening polymerisation was developed using boronate-urea (BU) as a representative LPHBD combined with tertiary amines.

Isatin pentafluorophenylhydrazones: interesting conformational change during anion sensing

Easily synthesized and highly efficient F⁻ and CH₃COO⁻ anion sensors based on reversible keto (hydrazo)/enolate (azo) acid–base equilibrium followed by interesting conformational change in solution.

1-Methyl-3-phenylthiourea

The title compound, C8H10N2S, was prepared by reaction of methylamine solution, KOH and phenyl-isothiocyanate in ethanol. It adopts asyn-Me andanti-Ph conformation relative to the C=S double bond. The dihedral angle between the N—C(=S)—N thiourea and phenyl planes is 67.83 (6)°. In the crystal, the molecules centrosymmetrical dimers by pairs of N(Ph)—H...S hydrogen bonds. The dimers are linked by N(Me)—H...S hydrogen bonds into layers parallel to (100).

Isatinphenylsemicarbazones as efficient colorimetric sensors for fluoride and acetate anions - anions induce tautomerism

The anion induced tautomerism of isatin-3-4-phenyl(semicarbazone) derivatives is studied herein. The interaction of F(-), AcO(-), H2PO4(-), Br(-) or HSO4(-) anions with E and Z isomers of isatin-3-4-phenyl(semicarbazone) and N-methylisatin-3-4-phenyl(semicarbazone) as sensors influences the tautomeric equilibrium of these sensors in the liquid phase. This tautomeric equilibrium is affected by (1) the inter- and intra-molecular interactions' modulation of isatinphenylsemicarbazone molecules due to the anion induced change in the solvation shell of receptor molecules and (2) the sensor-anion interaction with the urea hydrogens. The acid-base properties of anions and the difference in sensor structure influence the equilibrium ratio of the individual tautomeric forms. Here, the tautomeric equilibrium changes were indicated by "naked-eye" experiment, UV-VIS spectral and (1)H NMR titration, resulting in confirmation that appropriate selection of experimental conditions leads to a high degree of sensor selectivity for some investigated anions. Sensors' E and Z isomers differ in sensitivity, selectivity and sensing mechanism. Detection of F(-) or CH3COO(-) anions at high weakly basic anions' excess is possible.

Anion receptor chemistry: highlights from 2011 and 2012

This review covers advances in anion complexation in the years 2011 and 2012. The review covers both organic and inorganic systems and also highlights the applications to which anion receptors can be applied such as self-assembly and molecular architecture, sensing, catalysis and anion transport.

Anion recognition and transport properties of sulfamide-, phosphoric triamide- and thiophosphoric triamide-based receptors

Studies of sulfamide, phosphoric triamide and thiophosphoric triamide-based organocatalysts show that the phosphorus containing systems are effective new hydrogen bonding motifs for the recognition and transport of anions.

Small neutral molecular carriers for selective carboxylate transport

A series of neutral thiourea receptors were found to mediate the antiport of chloride with a range of biologically relevant carboxylate anions across phospholipid bilayers. Simple structural modification of the carriers resulted in a change in the lactate/pyruvate transport selectivity.

Lipothioureas as Lipids for Gene Transfection: A Review

Non-viral gene therapy requires innovative strategies to achieve higher transfection efficacy. A few years ago, our group proposed bioinspired lipids whose interaction with DNA was not based on ionic interactions, but on hydrogen bonds. We thus developed lipids bearing a thiourea head which allowed an interaction with DNA phosphates through hydrogen bonds. After a proof of concept with a lipid bearing three thiourea functions, a molecular and cellular screening was performed by varying all parts of the lipids: the hydrophobic anchor, the spacer, the linker, and the thiourea head. Two lipothiourea-based structures were identified as highly efficient in vitro transfecting agents. The lipothioureas were shown to reduce non specific interactions with cell membranes and deliver their DNA content intracellularly more efficiently, as compared to cationic lipoplexes. These lipids could deliver siRNA efficiently and allowed specific cell targeting in vitro. In vivo, thiourea lipoplexes presented a longer retention time in the blood and less accumulation in the lungs after an intravenous injection in mice. They also induced luciferase gene expression in muscle and tumor after local administration in mice. Therefore, these novel lipoplexes represent an excellent alternative to cationic lipoplexes as transfecting agents. In this review we will focus on the structure activity studies that permitted the identification of the two most efficient thiourea lipids.