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Hypoxia occurs in different pathological settings as a consequence of poor vascularization, and it results in reduced efficacy of some current nosocomial treatments i. e. chemotherapy and photodynamic therapy. In order to overcome these boundaries, aromatic endoperoxides (EPOs) have been studied and proposed as oxygen‐releasing agents (ORAs) due to their ability to reversibly bind molecular oxygen (O2), liberating it upon suitable triggering. DFT calculation of the dissociation energy (Ediss) of the intramolecular O−O bridge and structural crystallographic data of synthesized and studied EPOs drove the design of an array of 9,10‐disubstituted anthracenes among which three candidates were carefully selected. Once optimized the synthesis of the aromatic substrates, for the first time the corresponding EPOs have been produced under continuous flow irradiation in the presence of a sub‐stoichiometric amount of a photosensitizer in organic solvents. The release of O2 could be obtained straightforwardly at 37.5 °C by thermolysis. In accordance with the calculated Ediss=3.2 kcal mol−1 and an experimental t1/2=40 minutes, 3,3′‐(anthracene‐9,10‐diyl)bis(prop‐2‐yn‐1‐ol) resulted as the best candidate for the sustained release of O2 under physiologically relevant conditions. Its exploitation as ORA to relieve hypoxia will be evaluated and described in due course. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of [Ru(H)2 (CO)(PPh3 )3 ] 1 with an equimolar amount of pyrrole-2-carboxylic acid (H2L1) leads to the homoleptic chelate derivative k2 (O,O)-[RuH(CO)(HL1 )(PPh3 )2 ] 2. Prolonged acetonitrile refluxing promotes an unusual k2 (O,O)- → k2 (N,O)- dynamic chelate conversion, forming a neutral, stable, air- and moisture- insensitive, solvento-species k2 (N,O)-[Ru(MeCN) (CO)(L1 )(PPh3 )2 ] 3. Analogously, reaction of 1 with the pyrrole-2-carboxyaldehyde (HL2) affords k2 (N,O)-[RuH(CO)(HL2 )(PPh3 )2 ] 4, 5, as a couple of functional isomers. Optimized reaction conditions such as temperature and solvent polarity allow the isolation of dominant configurations. Structure 5 is a pyrrolide Ru-carbaldehyde, obtained from cyclization of the pendant CHO function, whereas species 4 can be viewed as an ethanoyl-conjugated Ru-pyrrole. Derivatives 3–5 were characterized by single crystal X-ray diffraction, ESI-Ms, IR, and NMR spectroscopy, indicating distinct features for the Ru-bonded pyrrolyl groups. DFT computational results, coplanarity, bond equalization, and electron delocalization along the fused five-membered rings support aromatic features. In accordance with the antisymbiotic trans-influence, both the isolated isomers 4 and 5 disclose CO ligands opposite to N- or O-anionic groups. The quantitative Mayer bond order evidences a stabilizing backbonding effect. Antibacterial and antifungal trials on Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli), and Candida albicans were further carried out. [ABSTRACT FROM AUTHOR]

The first site‐selective electrochemical alkylation of tropones is realized by reacting 2‐acetoxytropones and redox‐active‐esters (RAEs). The electroreductive protocol enables the preparation of mono‐ and disubstituted tropones in high yields (up to 71%) under very mild conditions. Dedicated voltammetric measurements served for the identification of 2‐acetoxytropones as a class of valuable trapping agents of nucleophilic radical species and shed light on the whole mechanistic profile. Wide tolerance towards functional groups (27 examples) and application to late‐stage functionalization of a bioactive compound (i. e. Colchicine analogue), emphasize the synthetic impact of the present methodology. [ABSTRACT FROM AUTHOR]

The "self-adaptability" of galvanostatic electrolysis was shown to assist a multistage unprecedented chemo- and diastereoselective electrochemically promoted cyclodimerization of chalcones. The process, all involving the reductive events, delivered densely functionalized cyclopentanes featuring five contiguous stereocenters (25 examples, yields of up to 95%, dr values up to >20 : 1). Dedicated and combined experimental as well as electrochemical investigation revealed the key role of a dynamic kinetic resolution of the aldol intermediate for the reaction mechanism. [ABSTRACT FROM AUTHOR]

The reaction of mer-(Ru(H)2(CO)(PPh3)3) (1) with one equivalent of thymine acetic acid (THAcH) unexpectedly produces the macrocyclic dimer k1(O), k2(N,O)-(Ru(CO)(PPh3)2THAc)2 (4) and, concomitantly, the doubly coordinated species k1(O), k2(O,O)-(Ru(CO)(PPh3)2THAc) (5). The reaction promptly forms a complicated mixture of Ru-coordinated mononuclear species. With the aim of shedding some light in this context, two plausible reaction paths were proposed by attributing the isolated or spectroscopically intercepted intermediates on the basis of DFT-calculated energetic considerations. The cleavage of the sterically demanding equatorial phosphine in the mer-species releases enough energy to enable self-aggregation, producing the stable, symmetric 14-membered binuclear macrocycle of 4. The k1-acetate iminol (C=N-OH) unit of the mer-tautomer k1(O)-(Ru(CO)(PPh3)2(THAc)) (2) likely exhibits a stronger nucleophilic aptitude than the prevalent N(H)-C(O) amido species, thus accomplishing extra stabilization through concomitant k2(N,O)-thymine heteroleptic side-chelation. Furthermore, both the ESI-Ms and IR simulation spectra validated the related dimeric arrangement in solution, in agreement with the X-ray determination of the structure. The latter showed tautomerization to the iminol form. The 1H NMR spectra in chlorinated solvents of the kinetic mixture showed the simultaneous presence of 4 and the doubly coordinated 5, in rather similar amounts. THAcH added in excess preferentially reacts with 2 or trans-k2(O,O)-(RuH(CO)(PPh3)2THAc) (3) rather than attacking the starting Complex 1, promptly forming the species of 5. The proposed reaction paths were inferred by spectroscopically monitoring the intermediate species, for which the results were strongly dependent on the of conditions the reaction (stoichiometry, solvent polarity, time, and the concentration of the mixture). The selected mechanism proved to be more reliable, due to the final dimeric product stereochemistry. [ABSTRACT FROM AUTHOR]

The article titled "Front Cover: Structure-Based Design and in-Flow Synthesis of Aromatic Endoperoxides Acting as Oxygen Releasing Agents" in the European Journal of Organic Chemistry discusses a new method for synthesizing aromatic endoperoxides (EPOs) that can release oxygen to relieve hypoxia. Through computational calculations and crystallographic data, three novel EPOs were designed to bind and release singlet oxygen under green light irradiation, regenerating the parent compound. The authors, Marco Agnes, Adelaide Santagata, Daniele Veclani, Alessandro Venturini, Magda Monari, Paolo Dambruoso, and Ilse Manet, provide more information in their research article. [Extracted from the article]

The molecular and supramolecular features of three triangular copper(II) propionate secondary building units (SBUs) which form different, self-assembled, 3D metal-organic frameworks (MOFs) are reported. The compounds are remarkably active and selective catalysts or catalyst precursors for the mild peroxidative oxidation of cycloalkanes under mild conditions, into the corresponding alcohols and ketones.

Three sets of oligomers containing the 4-carboxy-5-methyloxazolidin-2-one (Oxd) moiety were synthesized in a study with the aim of checking whether these molecules are able to fold in ordered structures. A deeper insight into the CD spectra reveals that the secondary structure adopted by one set of oligomers is a beta-bend ribbon spiral, which is a subtype of the 3(sub 10)-helix.

The neutral mu3-OH capped trinuclear triangular copper pyrazolate complexes are obtained by reacting pyrazole with copper(II) carboxylates in the presence of water. The existence of trinuclear cores in solution is supported by the results of electrospray ionization mass spectrometry and by the analogies between solid-state and corresponding UV-vis spectroscopy.

The asymmetric aldol condensation of acetone with isatin, its N-alkylated derivatives, and 5-` is described. A new quaternary stereocenter is obtained with good enantioselectivity, which can easily be enriched by silica flash chromatography and the effect proved to be general for the class of compounds.

The almost quantitative formation of the triangular trinuclear copper derivative [Cu(sub 3)(Mu(sub 3)-OH)(Mu-pz)(sub 3)(MeCOO)(sub 2)(Hpz)](1) (Hpz=pyrazole), is simply achieved by adding Hpz to an ethanol solution of Cu (Me COO)(sub 2). H (sub 2) O. An X-ray molecular structure determination shows that the derivative is completely unsymmetric and that trinuclear units result assembled in an extended bidimensional network formed through acetate bridges and hydrogen bonds.

A carboxylative Ni-catalyzed tandem C–C σ-bond activation of cyclobutanones followed by CO2-electrophilic trapping is documented as a direct route to synthetically valuable 3-indanone-1-acetic acids. The protocol shows an adequate functional group tolerance and useful chemical outcomes (yield up to 76%) when AlCl3 is adopted as an additive. Manipulations of the targeted cyclic scaffolds and a mechanistic proposal based on experimental evidence complete the investigation. [ABSTRACT FROM AUTHOR]

Research has been conducted on the ligand metathesis silver-assisted reaction of the platinum(II) complex with acetonitrile. The results of the kinetic studies indicate that the silver assistance operates via an associative step.

Research describes the synthesis of four noble metal containing, heterobimetallic cubane-like cores, Mo(sub)3S(sub)4M' cluster cores, in which M' is substituted with Ru, Os, Rh, and Ir. The cluster compounds containing Rh and Ir are prepared in boiling methanol in the presence of PPh(sub)3.