Ammonium Formate-Pd/C as a New Reducing System for 1,2,4-Oxadiazoles. Synthesis of Guanidine Derivatives and Reductive Rearrangement to Quinazolin-4-Ones with Potential Anti-Diabetic Activity

1,2,4-Oxadiazole is a heterocycle with wide reactivity and many useful applications. The reactive O-N bond is usually reduced using molecular hydrogen to obtain amidine derivatives. NH4CO2H-Pd/C is here demonstrated as a new system for the O-N reduction, allowing us to obtain differently substituted acylamidine, acylguanidine and diacylguanidine derivatives. The proposed system is also effective for the achievement of a reductive rearrangement of 5-(2′-aminophenyl)-1,2,4-oxadiazoles into 1-alkylquinazolin-4(1H)-ones. The alkaloid glycosine was also obtained with this method. The obtained compounds were preliminarily tested for their biological activity in terms of their cytotoxicity, induced oxidative stress, α-glucosidase and DPP4 inhibition, showing potential application as anti-diabetics.

The use of microfluidic hardware in the synthesis of oligohexamethylene guanidine derivatives

Objectives. To develop a method for the microfluidic synthesis of oligohexamethylene guanidine salts in a flow-type reactor and to evaluate its effectiveness in relation to the synthesis in a traditional capacitive reactor and compare the purities of products obtained by these methods.Methods. The synthesis of oligohexamethylene guanidine bihydrocarbonate (OHMG-BHC) was done using microfluidic hardware and the classical approach in volume. The purity and structure of the resulting product were confirmed by 13C NMR spectroscopy and high-performance liquid chromatography (HPLC).Results. The 13C NMR spectrum of OHMG-BHC in classical bulk synthesis demonstrates that the product is unbranched and contains additionally unidentifiable impurities, in contrast to the sample obtained by the microfluidic method. Furthermore, the HPLC analysis showed that the OHMG-BHC sample synthesized using microfluidic technology has a 1.5-fold lower content than the initial monomers.Conclusions. The advantage of synthesizing OHMG-BHC in a flow-type reactor compared to the traditional method of synthesis in volume is demonstrated since a product with a higher degree of purity is obtained.

Magnetic silica particles functionalized with guanidine derivatives for microwave-assisted transesterification of waste oil

This study aimed to develop a facile synthesis procedure for heterogeneous catalysts based on organic guanidine derivatives superbases chemically grafted on silica-coated Fe3O4 magnetic nanoparticles. Thus, the three organosilanes that were obtained by reacting the selected carbodiimides (N,N′-dicyclohexylcarbodiimide (DCC), N,N′-diisopropylcarbodiimide (DIC), respectively 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) with 3-aminopropyltriethoxysilane (APTES) were used in a one-pot synthesis stage for the generation of a catalytic active protective shell through the simultaneous hydrolysis/condensation reaction with tetraethyl orthosilicate (TEOS). The catalysts were characterized by FTIR, TGA, SEM, BET and XRD analysis confirming the successful covalent attachment of the organic derivatives in the silica shell. The second aim was to highlight the capacity of microwaves (MW) to intensify the transesterification process and to evaluate the activity, stability, and reusability characteristics of the catalysts. Thus, in MW-assisted transesterification reactions, all catalysts displayed FAME yields of over 80% even after 5 reactions/activation cycles. Additionally, the influence of FFA content on the catalytic activity was investigated. As a result, in the case of Fe3O4@SiO2-EDG, a higher tolerance towards the FFA content can be noticed with a FAME yield of over 90% (for a 5% (weight) vs oil catalyst content) and 5% weight FFA content.

Development of a Promising Method for Producing Oligomeric Mixture of Branched Alkylene Guanidines to Improve Substance Quality and Evaluate Their Antiviral Activity against SARS-CoV-2

This paper reports the synthesis of branched alkylene guanidines using microfluidic technologies. We describe the preparation of guanidine derivatives at lower temperatures, and with significantly less time than that required in the previously applicable method. Furthermore, the use of microfluidics allows the attainment of high-purity products with a low residual monomer content, which can expand the range of applications of this class of compounds. For all the samples obtained, the molecular-weight characteristics are calculated, based on which the optimal condensation conditions are established. Additionally, in this work, the antiviral activity of the alkylene guanidine salt against the SARS-CoV-2 virus is confirmed.

GUANIDINE: A SIMPLE MOLECULE WITH GREAT POTENTIAL: FROM CATALYSTS TO BIOCIDES AND MOLECULAR GLUES

This review is devoted to the general methods for obtaining guanidine derivatives and related compounds, their chemical properties, and structural features. On the one hand, guanidine and its derivatives play a crucial role in the metabolism of living organisms. On the other hand, owing to their unique properties and simple synthesis, the guanidine derivatives are used as synthetic drugs and biocidal agents, catalysts, ligands, and sweeteners. Furthermore, the guanidine derivatives serve as a basis for the creation of modern smart materials.

Robust and color-tunable afterglows from guanidine derivatives

Robust and color-tunable afterglows are readily achieved from guanidine derivatives, i.e. dicyandiamide and glycocyamine, through the synergy interplay between the clustering of electron-rich units and effective hydrogen bonding.