Synthesis and Characterization of Biguanide and Biguanidium Surfactants for Efficient and Recyclable Application in the Suzuki-Miyaura Reaction

Dual function surfactants for pharmaceutical formulations: The case of surface active and antibacterial 1-tolyl alkyl biguanide derivatives

One interesting field of research in the view of developing novel surfactants for pharmaceutical and cosmetic applications is the design of amphiphiles showing further bioactive properties in addition to those commonly displayed by surface-active compounds. We propose here the chemical synthesis, and characterization of 1-o-tolyl alkyl biguanide derivatives, having different lengths of the hydrocarbon chain (C3, C6, and C10), and showing surface active and antibacterial/disinfectant activities toward both Gram-positive and Gram-negative bacteria. Both surface active properties in terms of critical micelle concentration (CMC) and surface tension at CMC (γCMC), as well as the antimicrobial activity in terms of minimum inhibitory concentrations (MICs), were strongly dependent on the length of the hydrocarbon chain. Particularly, the C6 and C10 derivatives have a good ability to decrease surface tension (γCMC <40 mN/m) at low concentrations (CMC < 12 mM) and a satisfactory antibacterial effect (MIC values between 0.230 and 0.012 mM against S. aureus strains and between 0.910 and 0.190 against P.aeruginosa strains). Interestingly, these compounds showed a disinfectant activity at the tested concentrations that was comparable to that of the reference compound chlorhexidine digluconate. All these results support the possible use of these amphiphilic compounds as antibacterial agents and disinfectants in pharmaceutical or cosmetic formulations.

Fluorinated triphenylphosphonium analogs improve cell selectivity and in vivo detection of mito-metformin

Triphenylphosphonium (TPP⁺) conjugated compounds selectively target cancer cells by exploiting their hyperpolarized mitochondrial membrane potential. To date, studies have focused on modifying either the linker or the cargo of TPP⁺-conjugated compounds. Here, we investigated the biological effects of direct modification to TPP⁺ to improve the efficacy and detection of mito-metformin (MMe), a TPP⁺-conjugated probe we have shown to have promising preclinical efficacy against solid cancer cells. We designed, synthesized, and tested trifluoromethyl and methoxy MMe analogs (pCF₃-MMe, mCF₃-MMe, and pMeO-MMe) against multiple distinct human cancer cells. pCF₃-MMe showed enhanced selectivity toward cancer cells compared to MMe, while retaining the same signaling mechanism. Importantly, pCF₃-MMe allowed quantitative monitoring of cellular accumulation via ¹⁹F-NMR in vitro and in vivo. Furthermore, adding trifluoromethyl groups to TPP⁺ reduced toxicity in vivo while retaining anti-tumor efficacy, opening an avenue to de-risk these next-generation TPP⁺-conjugated compounds.

Mild Biamidine-Transfer Conditions for the Synthesis of Aliphatic Biguanides

This study focuses on the development of new synthetic pathways to monosubstituted biguanides from amines. An exhaustive comparison of the conditions and reagents used for biamidine transfer was performed. New reagents were synthesized and optimized conditions for the synthesis of substituted biguanides under mild conditions were developed. Eventually, two high-yielding and straightforward protocols for the transfer of a biamidine group to various amines are proposed and their scope and limitations have been explored. These conditions include: i) a direct chromatography-free procedure and ii) an eco-friendly procedure in water compatible with bioinspired molecules. They are particularly efficient for the demanding conversion of aliphatic amines.

Probing the catalytic activity of highly efficient sulfonic acid fabricated cobalt ferrite magnetic nanoparticles for the clean and scalable synthesis of dihydro, spiro and bis quinazolinones

An exceptionally productive, rapid, simple, and eco-friendly approach for the synthesis of 2,3-dihydroquinazolin-4(1H)-one has been developed utilizing acidic magnetically retrievable cobalt ferrite nanoparticles (CFNP@SO3H).

Recent advances on micellar catalysis in water

Water is the universal solvent in nature to catalyze the biological transformation processes. However, owing to the immiscibility of many reagents in water, synthesis chemistry relies heavily on organic solvent. Micellar media is a green alternative to traditional petroleum feedstock derived solvents, which is recently attracting increasing research attention. The present review deals with the recent advances in micellar catalysis with an emphasis on the new "tailor-made" surfactants for various reactions. A brief overview of commercial surfactants, including anionic micelles, cationic micelles, and nonionic micelles is presented. More importantly, an attempt was made to discuss systematically the recent research progress on new surfactants by introducing structures, micellar effects and recycling process, aiming to serve as the basis for future development of surfactants.

Efficient N-formylation of primary aromatic amines using novel solid acid magnetic nanocatalyst

Sulfonic acid functionalized over biguanidine fabricated silica-coated heterogeneous magnetic nanoparticles (NP@SO₃H) have been synthesized, well characterized and explored for the first time, as an efficient and recyclable catalyst for N-formylation of primary amines under mild reaction conditions. Exploiting the magnetic nature of Fe₃O₄, the prepared catalyst was readily recovered from the reaction mixture via an external magnet. The catalyst can be reused for up to six cycles without any substantial loss of catalytic activity. The cost effectiveness, simple methodology, wide substrate tolerance, excellent yield and easy work-up are the additional advantages of present catalytic system.

Sulfonic acid functionalized over biguanidine fabricated silica-coated heterogeneous magnetic nanoparticles (NP@SO₃H) have been synthesized, well characterized and explored for the first time, as an efficient and recyclable catalyst for N-formylation of primary amines under mild reaction conditions.

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki-Miyaura Cross-Coupling Reaction

Nickel catalysts represent a low cost and environmentally friendly alternative to palladium-based catalytic systems for Suzuki-Miyaura cross-coupling (SMC) reactions. However, nickel catalysts have suffered from poor air, moisture, and thermal stabilities, especially at high catalyst loading, requiring controlled reaction conditions. In this report, we examine a family of mono- and dinuclear Ni(II) and Pd(II) complexes with a diverse and versatile α-diimine ligand environment for SMC reactions. To evaluate the ligand steric effects, including the bite angle in the reaction outcomes, the structural variation of the complexes was achieved by incorporating iminopyridine- and acenaphthene-based ligands. Moreover, the impact of substrate bulkiness was investigated by reacting various aryl bromides with phenylboronic acid, 2-naphthylboronic acid, and 9-phenanthracenylboronic acid. Yields were the best with the dinuclear complex, being nearly quantitative (93-99%), followed by the mononuclear complexes, giving yields of 78-98%. Consequently, α-diimine-based ligands have the potential to deliver Ni-based systems as sustainable catalysts in SMC.

Structural features influencing the activity of bis-biguanide ligands in the Suzuki–Miyaura cross-coupling reaction in neat water

Catalytic reactions play an integral role in the development of green chemistry. Herein, we report new bis-biguanide compounds containing alkyl and aryl spacers as ligands for the Suzuki–Miyaura cross-coupling reaction in water. These ligands show similar catalytic activity to metformin independently of the nature of the spacer between the two biguanide units.

The chemistry of biguanides: from synthetic routes to applications in organic chemistry

In this minireview, we discuss the chemistry of biguanides and their applications in catalysis. We present their super basicity as a consequence of their structure, the most efficient ways to synthesize symmetric and unsymmetric functionalized biguanides, and their applications in organic catalysis as triazine precursors and ligands in organometallic catalysis.

Synthesis and characterization of new heterocycles related to aryl[e][1,3]diazepinediones. rearrangement to 2,4-diamino-1,3,5-triazine derivatives

Divergence-oriented synthesis of new heterocycles relevant for medicinal chemistry.

Size-Dependent Catalytic Activity and Fate of Palladium Nanoparticles in Suzuki-Miyaura Coupling Reactions

Stable, catalytically active palladium nanoparticles of various average diameters (1.9-7.4 nm) have been synthesized and characterized by X-ray diffraction, spectroscopy, and microscopy techniques to demonstrate remarkable size-dependent and renewed catalytic activity toward the Suzuki-Miyaura coupling reaction in green protocol. The catalytic activity is found to depend on the amount of the reducing agent, stabilizer-precursor ratio, solvent composition, and aryl halides used. The product obtained by this reaction is characterized by ¹H NMR, ¹³C NMR, and IR spectroscopy analyses. A newly developed kinetic equation illustrates that while the catalyst particles of the lowest dimension are gradually exposed to the reactants and hence activated due to partial removal of capping polymer from the catalyst surface, others are deactivated due to agglomeration during the progress of the reaction, as conformed by the microscopic profiles of the used and unused catalysts.