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.

Consequences of the electronic tuning of latent ruthenium-based olefin metathesis catalysts on their reactivity.

Two ruthenium olefin metathesis initiators featuring electronically modified quinoline-based chelating carbene ligands are introduced. Their reactivity in RCM and ROMP reactions was tested and the results were compared to those obtained with the parent unsubstituted compound. The studied complexes are very stable at high temperatures up to 140 °C. The placement of an electron-withdrawing functionality translates into an enhanced activity in RCM. While electronically modified precatalysts, which exist predominantly in the trans-dichloro configuration, gave mostly the RCM and a minor amount of the cycloisomerization product, the unmodified congener, which preferentially exists as its cis-dichloro isomer, shows a switched reactivity. The position of the equilibrium between the cis- and the trans-dichloro species was found to be the crucial factor governing the reactivity of the complexes.

Mechanistic studies of Hoveyda-Grubbs metathesis catalysts bearing S-, Br-, I-, and N-coordinating naphthalene ligands.

Derivatives of the Hoveyda-Grubbs complex bearing S-, Br-, I-, and N-coordinating naphthalene ligands were synthesized and characterized with NMR and X-ray studies. Depending on the arrangement of the coordinating sites on the naphthalene core, the isomeric catalysts differ in activity in model metathesis reactions. In particular, complexes with the RuCH bond adjacent to the second aromatic ring of the ligand suffer from difficulties experienced on their preparation and initiation. The behavior most probably derives from steric hindrance around the double bond and repulsive intraligand interactions, which result in abnormal chemical shifts of benzylidene protons observed with (1) H NMR. Furthermore EXSY studies revealed that the halogen-chelated ruthenium complexes display an equilibrium, in which major cis-Cl2 structures are accompanied with small amounts of isomeric forms. In general, contents of the minor forms, measured at 80 °C, correlate with the observed activity trends of the catalysts, although some exceptions complicate the mechanistic picture. We assume that for the family of halogen-chelated metathesis catalysts the initiation mechanism starts with the cis-Cl2 ⇌trans-Cl2 isomerization, although further steps may become rate-limiting for selected systems.

Nanopore sequencing of chloroplast genome of Scapania undulata (L.) Dumort., 1835 (Scapaniaceae, Jungermanniales).

We performed long-read sequencing of the Scapania undulata (L.) Dumort. chloroplast genome with Oxford Nanopore Technology using improved flow cells (10.3). S. undulata is a leafy liverwort living on rocks in or near water in mountains. The size of the complete plastome sequence is 117,651 bp long, the large single copy (LSC) region is 80,606 bp long, the small single copy (SSC) region is 19,401 bp long. The nanopore sequencing allowed for the distinction of inverted repeats A and B (IRA, IRB) which were not identical. Guanine cytosine (GC) ratio is 33.7% for the complete chloroplast genome, for LSC and SSC are 31.7% and 30.6%. The phylogeny reconstruction shows that Scapania undulata is the sister to S. ciliata and S. griffithii.

Elastography of Endometrium in Women Taking Tamoxifen: A New Approach to an Old Diagnostic Problem.

Tamoxifen is a commonly used selective estrogen receptor modulator applied in the treatment for breast cancer. However, in the endometrium, Tamoxifen stimulates tissue growth, cellular transformation, the migration of the cells, and metastatic potential in endometrial cancer. Considering that uterine cancer is the most common neoplasm of the reproductive tract and the third most common neoplastic disease in women, the aim of this study was to investigate if applying elastography in examining the endometrium was beneficial for uterine cancer screening protocols in women on selective estrogen receptor modulator therapy. This study was based on the execution of a classic assessment of the endometrium that included the evaluation of the following: echogenicity, central endometrial stripe, presence of fluid in the uterine lumen, myometrium-endometrium interface, intensity of vascularization and vascular pattern. An ultrasound presentation was then processed and analyzed with elastography. The values of the elastography parameters demonstrated good consistency for the measurement of the softest endometrial layer thickness in elastography. A strong positive correlation (R = 0.56) was demonstrated between the endometrial thickness, as determined by ultrasound examination, and the softest endometrial layer in elastography (p < 0.001). The research showed that the elastography measurements of the width of the softest endometrium layer, based on a population of women taking Tamoxifen, appeared to be a promising option for endometrial cancer screening.