Mechanism of the Kinugasa Reaction Revisited.

The mechanism of the Kinugasa reaction, that is, the copper-catalyzed formation of β-lactams from nitrones and terminal alkynes, is re-evaluated by means of density functional theory calculations and in light of recent experimental findings. Different possible mechanistic scenarios are investigated using phenanthroline as a ligand and triethylamine as a base. The calculations confirm that after an initial two-step cycloaddition promoted by two copper ions, the resulting five-membered ring intermediate can undergo a fast and irreversible cycloreversion to generate an imine and a dicopper-ketenyl intermediate.

Polarclean/Water as a Safe and Recoverable Medium for Selective C2-Arylation of Indoles Catalyzed by Pd/C.

Herein, we report the use of nontoxic, water-miscible Polarclean as a safe dipolar aprotic solvent for the metal-catalyzed direct C2-H arylation of indoles using Pd/C as a catalyst. The developed method allows reaching excellent yields and regioselectivities, and it tolerates various substituents on both indole and diaryliodonium salt scaffolds. Polarclean is fully recoverable and reusable; it shows a very low leaching of the metal catalyst, allowing its complete recovery and reuse for at least six representative reaction runs.

C-H functionalization reactions under flow conditions.

C-H functionalization technologies have progressed enormously in the last decade as testified by the great number of publications that have appeared in the literature, which are receiving great attention from researchers from different areas of expertise. While most of the protocols reported realize the C-H functionalization processes under batch conditions, there is a growing interest in the development of continuous-flow procedures aiming at increasing the performances of established methodologies or the definition of otherwise unfeasible transformations. This review summarizes the application of flow technologies for the realization of C-H functionalization reactions.

Polarclean as a Sustainable Reaction Medium for the Waste Minimized Synthesis of Heterocyclic Compounds.

Herein we report the use of Rhodiasolv Polarclean as a novel polar aprotic solvent for the synthesis of decorated heterocycles via dipolar cycloaddition (isooxazoles) or intramolecular C-H functionalization processes (benzo-fused chromenes). The use of Polarclean allowed to isolate the final products in good yields by simple solid filtration or liquid-liquid phase separation, avoiding the need for chromatographic purification. Moreover, since in the synthesis of benzo-fused chromenes, the metal catalyst is retained in Polarclean, the catalyst/reaction medium can be easily reused for consecutive reaction runs, without any apparent loss in efficiency.

Towards Sustainable C-H Functionalization Reactions: The Emerging Role of Bio-Based Reaction Media.

In the last decade, transition-metal catalyzed C-H functionalization reactions have progressed enormously, becoming a useful tool in organic synthesis and a practical alternative to well-established methodologies. Very recently, research efforts have also been devoted to developing more sustainable C-H functionalization protocols, in order to increase their applicability. One of the most promising approaches in this sense is represented by the substitution of common reaction media with bio-based solvents.

Click-chemistry approaches to π-conjugated polymers for organic electronics applications.

Given the wide utility of click-chemistry reactions for the preparation of simple moieties within large architecturally complex materials, this minireview article aims at surveying papers exploring their scope in the area of π-conjugated polymers for application in organic electronics to enable advanced functional properties.

A Catalytic Peterson-like Synthesis of Alkenyl Nitriles.

A heterogeneous fluoride catalyst was found to enable the straightforward formation of alkenyl nitriles from the reaction of aldehydes and simple or substituted acetonitriles, in the presence of commercially available silazanes and in solvent-free conditions. The protocol afforded the products in good to excellent yields with selectivity values dependent on the nature of the substrates. It represents an alternative to classic approaches using stoichiometric strong bases, and the catalyst can be easily recovered and reused for consecutive cycles.

Elucidation of Mechanisms and Selectivities of Metal-Catalyzed Reactions using Quantum Chemical Methodology.

Quantum chemical techniques today are indispensable for the detailed mechanistic understanding of catalytic reactions. The development of modern density functional theory approaches combined with the enormous growth in computer power have made it possible to treat quite large systems at a reasonable level of accuracy. Accordingly, quantum chemistry has been applied extensively to a wide variety of catalytic systems.

PS-BEMP as a basic catalyst for the phospha-Michael addition to electron-poor alkenes.

PS-BEMP was used as a heterogeneous catalyst for the phospha-Michael addition of phosphorus nucleophiles to a variety of electron-poor alkenes. The addition reactions were generally performed with equimolar amounts of reagents under solvent free conditions. The protocol proved to be very efficient for the addition to aromatic, non-aromatic and cyclic ketones, giving good yields (78-85%) in all cases.

Catalytic Asymmetric Reactions of 4-Substituted Indoles with Nitroethene: A Direct Entry to Ergot Alkaloid Structures.

A domino Friedel-Crafts/nitro-Michael reaction between 4-substituted indoles and nitroethene is presented. The reaction is catalyzed by BINOL-derived phosphoric acid catalysts, and delivers the corresponding 3,4-ring-fused indoles with very good results in terms of yields and diastereo- and enantioselectivities. The tricyclic benzo[cd]indole products bear a nitro group at the right position to serve as precursors of ergot alkaloids, as demonstrated by the formal synthesis of 6,7-secoagroclavine from one of the adducts.

Neoadjuvant chemotherapy is not a contraindication for nipple sparing mastectomy.

Background: Nipple-sparing mastectomy (NSM) has been recently implemented to improve cosmetic outcome after mastectomy, but it is rarely considered today after neoadjuvant chemotherapy (NCH).

Patients And Methods: Among 275 NSMs performed from January 2007 to January 2015, 186 cases, with a minimum follow-up of 12 months, were carried out for invasive or intraductal carcinoma. Patients were considered for NSM if there were no clinical and radiological evidence of invasion or close proximity (<1 cm) to the nipple-areola complex (NAC).

Theoretical study of mechanism and stereoselectivity of catalytic Kinugasa reaction.

The mechanism of the catalytic Kinugasa reaction is investigated by means of density functional theory calculations. Different possible mechanistic scenarios are presented using phenanthroline as a ligand, and it is shown that the most reasonable one in terms of energy barriers involves two copper ions. The reaction starts with the formation of a dicopper-acetylide that undergoes a stepwise cycloaddition with the nitrone, generating a five-membered ring intermediate.

Agarsenone, a Cadinane Sesquiterpenoid from Commiphora erythraea.

Agarsenone (1), a new cadinane sesquiterpenoid, was isolated from the resin of Commiphora erythraea. The structures of 1 and its decomposition products agarsenolides (2a and 2b) and myrrhone (3) were established by extensive NMR spectroscopic analysis. The absolute configuration of 3 and the relative and absolute configurations of 1 were assigned by comparison of experimental and calculated optical rotatory dispersion and electronic circular dichroism spectra.

Arylation with unsymmetrical diaryliodonium salts: a chemoselectivity study.

Phenols, anilines, and malonates have been arylated under metal-free conditions with twelve aryl(phenyl)iodonium salts in a systematic chemoselectivity study. A new "anti-ortho effect" has been identified in the arylation of malonates. Several "dummy groups" have been found that give complete chemoselectivity in the transfer of the phenyl moiety, irrespective of the nucleophile.

Enzyme-like catalysis via ternary complex mechanism: alkoxy-bridged dinuclear cobalt complex mediates chemoselective O-esterification over N-amidation.

Hydroxy group-selective acylation in the presence of more nucleophilic amines was achieved using acetates of first-row late transition metals, such as Mn, Fe, Co, Cu, and Zn. Among them, cobalt(II) acetate was the best catalyst in terms of reactivity and selectivity. The combination of an octanuclear cobalt carboxylate cluster [Co4(OCOR)6O]2 (2a: R = CF3, 2b: R = CH3, 2c: R = (t)Bu) with nitrogen-containing ligands, such as 2,2'-bipyridine, provided an efficient catalytic system for transesterification, in which an alkoxide-bridged dinuclear complex, Co2(OCO(t)Bu)2(bpy)2(μ2-OCH2-C6H4-4-CH3)2 (10), was successfully isolated as a key intermediate.

A mesenteric hernia complicated with a triple necrotic volvulus.

A 6-year-old girl was admitted to the paediatric emergency department with colicky abdominal pain. She had a significant medical history, with four previous admissions due to recurrent abdominal pain in the past year. On examination the abdomen was soft, there was no rebound tenderness and Rovsing's sign was negative.

Rheological properties of cross-linked hyaluronic acid dermal fillers.

Aim: Ha based dermal fillers in recent years aroused big interest in the area of cosmetic surgery for the rejuvenation of the dermis. There is not a ideal dermal filler (DF) for all applications and in commerce there are many types of DF that differ for their chemical-physical properties. So the aim of this paper is to correlate the rheological and physical properties of different DF to their clinical effectiveness.

Theoretical study of mechanism and selectivity of copper-catalyzed C-H bond amidation of indoles.

Density functional theory calculations are used to study the reaction mechanism and origins of C2 selectivity in a copper(I)-catalyzed amidation of indoles. It is shown that concerted metalation-deprotonation is not able to reproduce the observed regioselectivity. Instead, an unprecedented mechanism based on a four-center reductive elimination is proposed to be responsible for the reaction outcome.

A general phosphoric acid-catalyzed desymmetrization of meso-aziridines with silylated selenium nucleophiles.

The first example of meso-aziridine desymmetrization with selenium nucleophiles is reported. The reaction, promoted by VAPOL-hydrogen phosphate using (phenylseleno)trimethylsilane as the nucleophile, proves to be very general and highly enantioselective (84-99% ee).

Synthetic studies on the solanacol ABC ring system by cation-initiated cascade cyclization: implications for strigolactone biosynthesis.

We report a new method for constructing the ABC ring system of strigolactones, in a single step from a simple linear precursor by acid-catalyzed double cyclization. The reaction proceeds with a high degree of stereochemical control, which can be qualitatively rationalized using DFT calculations. Our concise synthetic approach offers a new model for thinking about the (as yet) unknown chemistry that is employed in the biosynthetic pathways leading to this class of plant hormones.

Cationic cyclization of 2-alkenyl-1,3-dithiolanes: diastereoselective synthesis of trans-decalins.

An unprecedented and highly diastereoselective 6-endo-trig cyclization of 2-alkenyl-1,3-dithiolanes has been developed yielding trans-decalins, an important scaffold present in numerous di- and triterpenes. The novelty of this 6-endo-trig cyclization stands in the stepwise mechanism involving 2-alkenyl-1,3-dithiolane, acting as a novel latent initiator. It is suggested that the thioketal opens temporarily under the influence of TMSOTf, triggering the cationic 6-endo-trig cyclization, and closes after C-C bond formation and diastereoselective protonation to terminate the process.

Skin/nipple sparing mastectomies and implant-based breast reconstruction in patients with large and ptotic breast: oncological and reconstructive results.

In this study we performed 77 procedures on 65 patients fulfilling the oncological criteria for skin-sparing mastectomy and presenting with large or medium size breasts. All the operations were performed as a single-stage procedure with an anatomical prosthesis allocated into a compound pouch, made up of the pectoralis major, serratus anterior fascia, and a lower dermal adipose flap. The medium size of the anatomical implants employed was 444.