Ammonia Borane Dehydrogenation Promoted by a Pincer-Square-Planar Rhodium(I) Monohydride: A Stepwise Hydrogen Transfer from the Substrate to the Catalyst

The pincer d8-monohydride complex RhH{xant(PiPr2)2} (xant(PiPr2)2 = 9, 9-dimethyl-4, 5-bis(diisopropylphosphino)xanthene) promotes the release of 1 equiv of hydrogen from H3BNH3 and H3BNHMe2 with TOF50% values of 3150 and 1725 h–1, to afford [BH2NH2]n and [BH2NMe2]2 and the tandem ammonia borane dehydrogenation–cyclohexene hydrogenation. DFT calculations on the ammonia borane dehydrogenation suggest that the process takes place by means of cis-¿2-PP-species, through four stages including: (i) Shimoi-type coordination of ammonia borane, (ii) homolytic addition of the coordinated H–B bond to afford a five-coordinate dihydride-boryl-rhodium(III) intermediate, (iii) reductive intramolecular proton transfer from the NH3 group to one of the hydride ligands, and (iv) release of H2 from the resulting square-planar hydride dihydrogen rhodium(I) intermediate

Trends and outcome of neoadjuvant treatment for rectal cancer: A retrospective analysis and critical assessment of a 10-year prospective national registry on behalf of the Spanish Rectal Cancer Project

Introduction: Preoperative treatment and adequate surgery increase local control in rectal cancer. However, modalities and indications for neoadjuvant treatment may be controversial. Aim of this study was to assess the trends of preoperative treatment and outcomes in patients with rectal cancer included in the Rectal Cancer Registry of the Spanish Associations of Surgeons. Method: This is a STROBE-compliant retrospective analysis of a prospective database. All patients operated on with curative intention included in the Rectal Cancer Registry were included. Analyses were performed to compare the use of neoadjuvant/adjuvant treatment in three timeframes: I)2006–2009; II)2010–2013; III)2014–2017. Survival analyses were run for 3-year survival in timeframes I-II. Results: Out of 14, 391 patients, 8871 (61.6%) received neoadjuvant treatment. Long-course chemo/radiotherapy was the most used approach (79.9%), followed by short-course radiotherapy ± chemotherapy (7.6%). The use of neoadjuvant treatment for cancer of the upper third (15-11 cm) increased over time (31.5%vs 34.5%vs 38.6%, p = 0.0018). The complete regression rate slightly increased over time (15.6% vs 16% vs 18.5%; p = 0.0093); the proportion of patients with involved circumferential resection margins (CRM) went down from 8.2% to 7.3%and 5.5% (p = 0.0004). Neoadjuvant treatment significantly decreased positive CRM in lower third tumors (OR 0.71, 0.59–0.87, Cochrane-Mantel-Haenszel P = 0.0008). Most ypN0 patients also received adjuvant therapy. In MR-defined stage III patients, preoperative treatment was associated with significantly longer local-recurrence-free survival (p < 0.0001), and cancer-specific survival (p < 0.0001). The survival benefit was smaller in upper third cancers. Conclusion: There was an increasing trend and a potential overuse of neoadjuvant treatment in cancer of the upper rectum. Most ypN0 patients received postoperative treatment. Involvement of CRM in lower third tumors was reduced after neoadjuvant treatment. Stage III and MRcN + benefited the most

Colorants fluorats hidrofòbics i el seu ancoratge sobre materials

Artificial hydrophobic surfaces have a great potential in a wide range of industrial applications owing to their self-cleaning, anti-biofouling, anti-fogging, anti-sticking, anti-corrosion and anti-contamination properties. Equipment for fibers and textiles with hydrophobic properties is of high interest for fabrics with water, oil or soil repellent properties, e.g. for special sports clothes, home textiles like carpets or upholstered furniture, and some outdoor materials, such as umbrellas. Continuing along the line of research of our group, functional reactive dyes with different chromatic cores have been prepared with long polyfluorinated chains in their structure, and functional groups that allow their grafting on a cotton fabric surface or on glass, obtaining new colored hydrophobic materials. Contact angle measurements have been made of a droplet of water on the surface of stained fabrics and on glass coated with our new compounds. Angles higher than 150o have been obtained on the stained fabrics, proving that they are superhydro-phobic

Nucleophilic aromatic substitution on 4-fluorophenylsulfonamides: Nitrogen, oxygen, and sulfur nucleophiles

Improved conditions are reported for the stoichiometric reaction of nitrogen, oxygen, and sulfur nucleophiles with weakly activated 4-fluorophenylsulfonamides. © Georg Thieme Verlag Stuttgart

Wide temperature range mesomorphic behaviour of highly fluorinated 15-membered macrocycles and their open trisulphonamide precursor

The mesomorphic properties of 15-membered azamacrocycles containing long hydrocarbon or highly fluorinated long chains have been explored along with those of their open precursors. The liquid crystalline behaviour is determined by the presence of different heteroatoms or long fluorinated chains and the substitution pattern of the aryl units of the sulphonamides. The presence of highly fluorinated long chains in the para position with regard to the sulphonamide group was found to favour the formation of smectic mesophases with wide temperature ranges. All of the mesophases were studied by polarizing optical microscopy and differential scanning calorimetry. © 2007 Taylor & Francis

Structure of chiral pyrazoles in the solid state and in solution

The X-ray molecular structures of three chiral pyrazoles bearing (4S)-4-benzyloxazolidin-2-ones or (2R)-bornane- 10,2-sultams at position 3(5) have been studied by single crystal X-ray di raction and by NMR. In the solid state, the same pyrazole tautomer a has been found for the three compounds, that with the chiral group in the 3-position. Their crystal structures consist of inÐnite chains (catemers) formed by NÈHÉÉÉO2X (X : C, S) hydrogen bonds. The use of solid-state 13C NMR spectroscopy demonstrated that the pyrazole is also an a tautomer. 13C NMR spectra in methanol solution yield average signals even at [80 ¡C ; nevertheless, interpolation allows one to estimate that in solution tautomer a also predominates.We are indebted to MEC of Spain (Projects PB93-0896 and PB98-0902) and Generalitat de Catalunya (Project 1998SGR- 0056 and a scholarship to R. M. S.) for Ðnancial support, and to URQUIMA, S. A. (Dr Joan for a generous gift of Blade) oxazolidinone. We thank the Departamento de Química y (UNED) for recording the CPMASOrgánica Biología spectra of compounds 1 and 2.Peer reviewe

Nuevas sustancias colorantes y el procedimiento para su obtención

Nuevas sustancias permanentes e hidrófobas, procedimiento para su obtención y uso de dichos colorantes en medios altamente fluorados