Nitro-Grela-type complexes containing iodides – robust and selective catalysts for olefin metathesis under challenging conditions

Iodide-containing nitro-Grela-type catalysts have been synthesized and applied to ring closing metathesis (RCM) and cross metathesis (CM) reactions. These new catalysts have exhibited improved efficiency in the transformation of sterically, non-demanding alkenes. Additional steric hindrance in the vicinity of ruthenium related to the presence of iodides ensures enhanced catalyst stability. The benefits are most apparent under challenging conditions, such as very low reaction concentrations, protic solvents or with the occurrence of impurities

Effective immobilisation of a metathesis catalyst bearing an ammonium-tagged NHC ligand on various solid supports

An ammonium-tagged ruthenium complex, 8, was deposited on several widely available commercial solid materials such as silica gel, alumina, cotton, filter paper, iron powder or palladium on carbon. The resulting catalysts were tested in toluene or ethyl acetate, and found to afford metathesis products in high yield and with extremely low ruthenium contamination. Depending on the support used, immobilised catalyst 8 shows also additional traits, such as the possibility of being magnetically separated or the use for metathesis and subsequent reduction of the obtained double bond in one pot

2‑Methyltetrahydrofuran as a Solvent of Choice for Spontaneous Metathesis/Isomerization Sequence

A new protocol for ring-closing metathesis/isomerization sequence was developed. The reactions of selected dienes were performed in overheated 2-methyltetrahydrofuran at 120 °C and provided a wide range of cyclic vinyl ethers and amides with good yields and selectivities. Computational analysis suggests that the relative yield of products depends on a thermodynamically driven process on the basis of relative stabilities of isomers

Cyclic Alkyl Amino Ruthenium Complexes—Efficient Catalysts for Macrocyclization and Acrylonitrile Cross Metathesis

ABSTRACT: The active species generated from ruthenium complexes bearing N-heterocyclic carbene (NHC) ligands exhibit limited stability under certain conditions (high dilution, high temperature) and in the presence of nitrile functionality. As a consequence, industrial implementation of metathesis for the production of important materials such as macrocyclic musks and polyamide 11 is uneconomical. Over the past decade, hundreds of ruthenium complexes bearing NHC ligands have been obtained. However, to this date, they have brought rather limited improvements in efficiency. In this paper, we report on cyclic alkyl amino carbene (CAAC) ruthenium complexes that promote highly challenging macrocyclization and cross metathesis (CM) with acrylonitrile reactions at loadings as low as 10−20 ppm

Jakość życia pacjentów z napadowym migotaniem przedsionków po ablacji okrążającej żył płucnych

Background: Atrial fibrillation (AF) is the most common arrhythmia and is associated with a deterioration of quality of life (QoL). Catheter ablation is a therapeutic strategy for some patients with AF. The effectiveness of pulmonary vein isolation is still under assessment. Aim: To assess the long-term influence of circumferential pulmonary vein ablation (CPVA) on QoL in patients with AF. Methods: The study population consisted of 33 patients (26 males, age 54.2 ± 9 years) with highly symptomatic (EHRA II–III) drug refractory paroxysmal AF, who underwent CPVA. A clinical examination, electrocardiogram (ECG), and Holter ECG were performed before and during a one-year follow-up. The SF-36 Medical Outcomes Survey Short-Form QoL questionnaire, scored on a 0–100 scale for each of eight domains: bodily pain (BP), general health (GH), mental health (MH), physical functioning (PF), role-emotional (RE), role-physical (RP), social functioning (SF), and vitality (V), was collected before and one year after CPVA. Results: In the one-year follow-up 27 (82%) patients were free of AF. EHRA symptoms were improved one-year after CPVA regardless of CPVA efficacy. After the follow-up the SF-36 questionnaire results improved significantly in all of the subscales in patients without a recurrence of AF after CPVA. In subjects with a recurrence of AF, all of the subscales did not indi­cate any statistically significant differences. There was an association between the CPVA and the following QoL domains: GH (p = 0.018), PF (p = 0.042), and V (p = 0.041). The highest values of the GH and V domains were found in the non-re­currence patients one year after CPVA. Conclusions: CPVA results in the clinical improvement of patients with symptomatic AF regardless of the final arrhythmia termination. Patients after successful CPVA experienced a significant improvement in all of the subscales of the QoL.Wstęp: Migotanie przedsionków (AF) jest jedną z najczęstszych arytmii i wiąże się z pogorszeniem jakości życia (QoL). Izolacja żył płucnych (CPVA) jest jedną z metod terapeutycznych wykorzystywaną u objawowych pacjentów z AF, a jej kompleksowe efekty są wciąż w fazie oceny. Cel: Celem pracy była obserwacja odległych wyników CPVA i ich wpływ na QoL chorych z AF przed i po CPVA. Metody: Badaniem objęto 33 pacjentów (26 mężczyzn), w wieku: 54,2 ± 9 lat z symptomatycznym opornym na farmakote­rapię AF (EHRA II–III), którzy byli poddani CPVA. Badania kliniczne, elektrokardiograficzne (EKG) oraz EKG metodą Holtera i SF-36 przeprowadzono przed, a także rok po CPVA. Jakość życia oceniano za pomocą Kwestionariusza SF-36 Survey Short­-Form. W formularzu SF-36 zastosowano skalę 0–100 dla każdego z 8 parametrów QoL, takich jak: odczucie bólu (BP), ogólny stan zdrowia (GH), stan zdrowia psychicznego (MH), funkcjonowanie fizyczne (PF), stan emocjonalny (RE), stan cielesny (RP), funkcjonowanie społeczne (SF) i witalność (V). Wyniki: Po roku od zabiegu CPVA 27 (82%) pacjentów nie miało napadów AF. Objawy AF (w skali EHRA) uległy zmniejszeniu niezależnie od skuteczności CPVA. Analiza QoL wykazała znaczną poprawę w zakresie wszystkich ocenianych parametrów u pacjentów bez nawrotu arytmii. U chorych z nawrotem AF żaden oceniany parametr QoL nie wykazywał istotnych zmian po roku obserwacji. Stwierdzono związek między CPVA i następującymi parametrami QoL: GH (p = 0,018), PF (p = 0,042), V (p = 0,041). Najwyższe wartości GH i V wykazano u chorych bez nawrotu AF w czasie roku po CPVA. Wnioski: Zabieg CPVA prowadzi do redukcji objawów AF niezależnie od efektu, jakim jest ostateczne ustąpienie arytmii. Pacjenci po skutecznym CPVA odczuwają znaczną poprawę QoL w zakresie każdego ocenianego parametru

Nitration Under Continuous Flow Conditions: Convenient Synthesis of 2‑Isopropoxy-5-nitrobenzaldehyde, an Important Building Block in the Preparation of Nitro-Substituted Hoveyda–Grubbs Metathesis Catalyst

Herein, we describe the use of continuous flow chemistry for selective, efficient and reproducible nitration of 2-isopropoxybenzaldehyde to produce the desired 2-isopropoxy-5-nitrobenzaldehyde, an important building block in the preparation of a ligand of nitro-substituted Hoveyda–Grubbs metathesis catalyst. Nitration was done with red fuming HNO₃, and this challenging and hazardous process was performed using a flow-through silicon-glass microreactor equipped with a set of temperature sensors, and with a productivity of 13 g/h, providing us with a reproducible chemical process amenable for production of sufficient quantities of 2-isopropoxy-5-nitrobenzaldehyde for ongoing large-scale synthesis of nitro-substituted Hoveyda–Grubbs metathesis catalyst

Ru-Based Complexes with Quaternary Ammonium Tags Immobilized on Mesoporous Silica as Olefin Metathesis Catalysts

Ruthenium olefin metathesis catalysts bearing a polar quaternary ammonium group in N-heterocyclic ligand were immobilized on silica and siliceous mesoporous molecular sieves with different pore sizes (SBA-15 and MCM-41). The activity of the heterogeneous catalysts was found to increase with an increase in pore size of the support used, with the best results observed for SBA-15-supported catalyst. The influence of reaction conditions (temperature, solvent, catalyst, and substrate concentration) on the efficiency of new heterogeneous catalysts was established. A significant influence of the counterion present in the ruthenium complex on the activity of immobilized catalysts was also found: those derived from chloride containing ion exhibited the highest activity. High activity in ring-closing metathesis of substrates as citronellene, 1,7-octadiene, and diallyl compounds as well as in cross-metathesis of unsaturated aliphatic compounds with methyl acrylate was observed under optimized conditions. In some cases, heterogenization led to catalysts with efficiency higher than those observed for corresponding homogeneous complexes

Carboxyl Graphene as a Superior Support for Bulky Ruthenium-Based Olefin Metathesis Catalyst

A Hoveyda-type catalyst decorated with two quaternary ammonium tags was synthesized and noncovalently grafted on SiO₂, SBA-15, and on carboxyl graphene. A comparative study showed that the efficiency of the dual-anchored heterogeneous catalysts was highly dependent on the properties of the supporting material with graphene outperforming silicate supports. The graphene-immobilized complex exhibited excellent efficiency reflected in turnover numbers obtained in ring-closing metathesis and in self-metathesis of 1-decene. Importantly, the solid-supported catalyst assured increased recyclability with no ruthenium leaching as confirmed by inductively coupled plasma mass spectrometry