Regiodivergent formal [4+2] cycloaddition of nitrosoarenes with furanyl cyclopropane derivatives as 4π components.

Cyclopropanes are commonly used as valuable 3-carbon building blocks. Herein, we disclose a different reactivity pattern of furanyl cyclopropanes, which serve as a 4-carbon component in Lewis acid-promoted [4+2] cycloadditions with nitrosoarenes to afford 1,2-oxazine derivatives. Importantly, the regioselectivity of the cycloaddition reaction can be controlled by the appropriate choice of the Lewis acid.

One-Pot Regio- and Diastereoselective Gold-Catalyzed Propargylation of in Situ Activated Chromones and Consecutive Cyclization.

Herein, we report a gold-catalyzed propargylation of chromone derivatives by propargylsilanes. Chromones are synergistically activated by the silylium cation resulting from the gold activation of the propargylsilane. The reaction exclusively occurs at the C2-position of the chromone, and a single diastereoisomer is formed.

Photochemical carboborylation and three-component difunctionalization of α,β-unsaturated ketones with boronic acids tosylhydrazones.

The reactions of cyclic α,β-unsaturated -tosylhydrazones and alkylboronic acids promoted by 370-390 nm light in the presence of a base give rise to allylic boronic acids that can be trapped as the corresponding pinacolboronates by treatment with pinacol. This reaction features wide scope regarding both coupling partners and functional group tolerance, allowing for the incorporation of a variety of natural product-derived fragments. The allylic boronic acids can be also reacted in a one-pot process with aldehydes, to produce homoallylic alcohols with very high diastereoselectivity.

Visible-light-driven synthesis of alkenyl thiocyanates: novel building blocks for assembly of diverse sulfur-containing molecules.

The first visible-light-induced protocol for the general preparation of alkenyl thiocyanates from alkenyl bromides is presented. The reaction is simple, proceeds under very mild conditions and demonstrates broad functional group tolerance. Additionally, a flow protocol was developed to enable efficient scale-up of alkenyl thiocyanate synthesis, further enhancing the practicality and value of the method.

In the search for new gold metalloantibiotics: In vitro evaluation of Au(III) (C^S)-cyclometallated complexes.

A series of (C^S)-cyclometallated Au(III) cationic complexes of general formula [Au(dppta)(dtc)], [Au(dppta)(azmtd)] and [Au(dppta)(azc)Cl] (dppta = N,N-diisopropyl-P,P-diphenylphosphinothioic amide-κC,S; dtc = dithiocarbamate-κS,S'; azc = azolium-2-dithiocarboxylate-κS; azmdt = azol(in)ium-2-(methoxy)methanedithiol-κS,S') were synthetized and tested against a panel of bacterial strains belonging to different Gram-positive and Gram-negative species of the ESKAPE group of pathogens. Among the tested compounds, complex 4c had the higher Therapeutic Index (TI) against multidrug resistant strains of S. aureus, S.

Liposomal formulation of a gold(III) metalloantibiotic: a promising strategy against antimicrobial resistance.

A novel lipoformulation was developed by encapsulating cationic (S^C)-cyclometallated gold(III) complex [Au(dppta)(NPy-PZ-dtc)] (AuPyPZ) in liposomes. The liposomal form of compound AuPyPZ has a bactericidal action similar to that of the free drug without any appreciable effect on the viability of mammalian cells. Furthermore, the nanoformulation reduces metalloantibiotic-induced inhibition of hERG and the inhibition of cytochromes, significantly decreasing the potential liabilities of the metallodrug.

From Cyclopropene to Housane Derivatives Via Intramolecular Cyclopropanation.

The synthesis of housane derivatives from cyclopropenes is described. Under rhodium(II) catalysis, cyclopropenylvinyl carbinols can regioselectively generate a carbene intermediate which undergoes an intramolecular cyclopropanation to form a housane, a skeleton with similar ring strain as the cyclopropene precursor. The procedure shows a remarkable broad scope and efficiency.

Zinc amidinate-catalysed cyclization reaction of carbodiimides and alkynes. An insight into the mechanism.

A synthesis of iminopyridines based on zinc has been developed. The commercially available ZnEt was employed as a precatalyst for this process. A mechanism has been proposed on the basis of Density Functional Theory (DFT) studies and stoichiometric reactions.

1,2-Silyl Rearrangement in Gold Carbene Chemistry: Synthesis of Furyl-Decorated Tetrasubstituted Silylallene Derivatives.

The gold-catalyzed reaction of 2-en-4-ynones with alkynylsilanes provides fully substituted allene derivatives bearing furyl and silyl groups. This transformation would involve generation of a gold furyl carbene intermediate, which regioselectively undergoes a nucleophilic attack by the alkynylsilane at the electrophilic carbene carbon atom with the formation of a β-gold vinyl cation species. The subsequent release of the gold catalyst, accompanied by a 1,2-silyl shift, leads to the formation of tetrasubstituted allene products.

The synthesis of solid supports carrying base labile linkers to generate 3'-phosphate oligonucleotides.

Oligonucleotides carrying 3'-terminal phosphates and conjugates are important tools in molecular biology and diagnostic purposes. We described the preparation of solid supports carrying the base labile linker 4-((2-hydroxyethyl)sulfonyl)benzamide for the solid-phase synthesis of 3'-phosphorylated oligonucleotides. These supports are fully compatible with the phosphoramidite chemistry yielding the desired 3'-phosphate oligonucleotides in excellent yields.

Editorial for the Special Issue "Hydrogels for 3D Printing".

Hydrogels, which are three-dimensional networks of hydrophilic polymers capable of absorbing and retaining large amounts of water, have emerged as versatile materials with vast potential in various fields [...

Coordination of azol(in)ium dithiocarboxylate ligands to Au(III): unexpected formation of a novel family of cyclometallated Au(III) complexes, DFT calculations and catalytic studies.

A series of cyclometallated gold(III) complexes 21-27 of general formula [Au(dppta)(azdtc)Cl] (dppta = ,-diisopropyl-,-diphenylphosphinothioic amide-κC,S; azdtc = azol(in)ium-2-dithiocarboxylate-κS) were prepared and characterized by spectroscopic and diffractometric techniques. Treatment of [Au(dppta)(azdtc)Cl] complexes with methanol led to their quantitative transformation into a novel family of (C^S, S^S)-cyclometallated gold(III) complexes of general formula [Au(dppta)(azmtd)] (azmdt = azol(in)ium-2-(methoxy)methanedithiol-κS,S) 28-34. All the [Au(dppta)(azdtc)Cl] complexes 21-27 catalyzed the alkylation of indoles, whereas [Au(dppta)(azmtd)] complexes 28-34 were inactive.

Advancements in visible-light-induced reactions via alkenyl radical intermediates.

In recent years, visible-light-induced organic transformations have taken a central role driving forward the progress of modern organic synthesis. These processes typically involve the transient generation of highly reactive radical intermediates, facilitating a diverse array of chemical reactions. Despite the abundance of synthetic strategies enabling the access of aryl and alkyl-centered radicals, the exploitation of photochemistry to generate highly reactive alkenyl radicals has remained notably underdeveloped.

C≡N and N≡O Bond Cleavages of Acetonitrile and Nitrosyl Ligands at a Dimolybdenum Center to Render Ethylidyne and Acetamidinate Ligands.

Extended reduction of [MoCp(μ-Cl)(μ-PBu)(NO)] () with Na(Hg) in acetonitrile (MeCN) at room temperature resulted in an unprecedented full cleavage of the C≡N bond of a coordinated MeCN molecule to yield the vinylidene derivative Na[MoCp(μ-PBu)(μ-CCH)(NO)], which upon protonation with (NH)PF gave the ethylidyne complex [MoCp(μ-PBu)(μ-CMe)(NO)] [Mo1-Mo2 = 2.9218(2) Å] in a selective and reversible way. Controlled reduction of at 273 K yielded instead, after protonation, the 30-electron acetamidinate complex [MoCp(μ-PBu)(μ-κ:κ'-HNCMeNH)(μ-NO)]PF [Mo1-Mo2 = 2.

Synthesis of substituted benzylboronates by light promoted homologation of boronic acids with -sulfonylhydrazones.

The synthesis of benzylboronates by photochemical homologation of boronic acids with -tosylhydrazones under basic conditions is described. The reaction involves the photolysis of the -tosylhydrazone salt to give a diazoalkane followed by the geminal carboborylation of the diazoalkane. Under the mild reaction conditions, the protodeboronation of the unstable benzylboronic acid is circumvented and the pinacolboronates can be isolated after reaction of the benzylboronic acid with pinacol.

Photochemical halogen-bonding assisted carbothiophosphorylation reactions of alkenyl and 1,3-dienyl bromides.

Herein, we present a synthetic procedure for the facile and general preparation of novel -alkenyl and dienyl phosphoro(di)thioates for the first time. Extensive mechanistic investigations support that the reactions rely on a photochemical excitation of a halogen-bonding complex, formed with a phosphorothioate salt and an alkenyl or dienyl bromide, which light-induced fragmentation leads to the formation of the desired products through a radical-based pathway. The substrate scope is broad and exhibits a wide functional group tolerance in the formation of the final compounds, including molecules derived from natural products, all with unknown and potentially interesting biological properties.

Recent Advances in the Catalytic Synthesis of the Cyclopentene Core.

Five-membered carbocycles are ubiquitously found in natural products, pharmaceuticals, and other classes of organic compounds. Within this category, cyclopentenes deserve special attention due to their prevalence as targets and as well as key intermediates for synthesizing more complex molecules. Herein, we offer an overview summarizing some significant recent advances in the catalytic assembly of this structural motif.

Pellets and gummies: Seeking a 3D printed gastro-resistant omeprazole dosage for paediatric administration.

The production of 3D printed pharmaceuticals has thrived in recent years, as it allows the generation of customised medications in small batches. This is particularly helpful for patients who need specific doses or formulations, such as children. Compounding pharmacies seek alternatives to conventional solid oral doses, opting for oral liquid formulations.

Essential Guide to Hydrogel Rheology in Extrusion 3D Printing: How to Measure It and Why It Matters?

Rheology plays a crucial role in the field of extrusion-based three-dimensional (3D) printing, particularly in the context of hydrogels. Hydrogels have gained popularity in 3D printing due to their potential applications in tissue engineering, regenerative medicine, and drug delivery. The rheological properties of the printing material have a significant impact on its behaviour throughout the 3D printing process, including its extrudability, shape retention, and response to stress and strain.

Shining light on halogen-bonding complexes: a catalyst-free activation mode of carbon-halogen bonds for the generation of carbon-centered radicals.

The discovery of new activation modes for the creation of carbon-centered radicals is a task of great interest in organic chemistry. Classical activation modes for the generation of highly reactive radical carbon-centered intermediates typically relied on thermal activation of radical initiators or irradiation with unsafe energetic UV light of adequate reaction precursors. In recent years, photoredox chemistry has emerged as a leading strategy towards the catalytic generation of C-centered radicals, which enabled their participation in novel synthetic organic transformations which is otherwise very challenging or even impossible to take place.

Gold-catalyzed -selective cyclization of alkynylcyclobutanecarboxamides: synthesis of cyclobutane-fused dihydropyridones.

Cyclobutane-fused dihydropyridones can be efficiently synthesized by a completely -selective gold-catalyzed cyclization of alkynylcyclobutanes bearing an appended amide, which proceeds under mild conditions. The observed selectivity, which is reversed from that previously observed for the cyclization of related alcohols and acids, is supported by DFT calculations.

Silylium-Catalyzed Regio- and Stereoselective Carbosilylation of Ynamides with Allylic Trimethylsilanes.

The regio- and stereoselective carbosilylation of tosylynamides with allylic trimethylsilanes takes place under mild conditions in the presence of catalytic TMSNTf or HNTf to give ()-α-allyl-β-trimethylsilylenamides with good yields. Theoretical calculations show the activation of the C-C triple bond of the ynamides by the trimethylsilylium ion and formation of a β-trimethylsilylketenimonium cation. Further transformations of the products demonstrate the synthetic utility of this reaction.

Photochemical halogen-bonding assisted generation of vinyl and sulfur-centered radicals: stereoselective catalyst-free C(sp)-S bond forming reactions.

The combination of photochemistry and halogen bonding interactions has risen in the last few years as a powerful synthetic tool for the creation of radical intermediates under mild conditions. In the formation of carbon-centered radicals, this reactivity has been to date restricted to the employment of aryl and alkyl halides as precursors. We now envisioned that the halogen-bonding initiated formation of highly reactive vinyl radicals would be a feasible process for the photochemical cross-coupling between thiols and alkenyl halides under basic conditions.

Intramolecular activation of strong Si-O bonds by gold(I): regioselective synthesis of 3-bromo-2-silylbenzofurans.

The high reactivity of gold-vinylidene complexes, generated by [1,2]-bromine shift from the corresponding 1-bromoalkynes, allows the activation of one of the strongest bonds in organic chemistry (Si-O), strategically placed at the -position. In this way, the synthesis of 3-bromo-2-silylbenzofuranes is achieved in good yields. Several substituents with different electronic properties and substitution patterns are well tolerated on the tethering aromatic ring as well as a number of silyl groups on the O-atom.