Direct Arylation in the Presence of Palladium Pincer Complexes.

Direct arylation is an atom-economical alternative to more established procedures such as Stille, Suzuki or Negishi arylation reactions. In comparison with other palladium sources and ligands, the use of palladium pincer complexes as catalysts or pre-catalysts for direct arylation has resulted in improved efficiency, higher reaction yields, and advantageous reaction conditions. In addition to a revision of the literature concerning intra- and intermolecular direct arylation reactions performed in the presence of palladium pincer complexes, the role of these remarkably active catalysts will also be discussed.

Vaginal residence and pharmacokinetic preclinical study of topical vaginal mucoadhesive W/S emulsions containing ciprofloxacin.

The aim of this work is to test the in vivo behavior of a mucoadhesive vaginal emulsion resistant to the clearance of vaginal fluids using ciprofloxacin (CPX) as an anti-infective model of drug. CPX is a broad-spectrum antibiotic used in the treatment of sexual tissues infections, as intravenous injection in a dose of 20 mg every 12 h. In this study, CPX was incorporated in water in silicone (W/S) mucoadhesive emulsions and the in vivo residence time and the CPX in vivo absorption and distribution to the sexual organs was studied using the rat as animal model. W/S emulsion shows excellent in vitro bioadhesion having high resistance to the vaginal fluids clearance. The drug release profiles show a constant release of CPX during at least 6 h according to a zero-order kinetics. In vivo computerized PET/CT Image Analysis after intravaginal administration to rats indicates that W/S emulsions remain in the vaginal area for a long time and shows a good absorption of the radiotracers used as markers through the vaginal mucosa. Ciprofloxacin pharmacokinetic studies developed after the single intravaginal administration of W/S emulsion shows a good absorption and distribution of CPX on the uterus and ovarian tissue. A significant concentration of CPX in the sexual tissues was observed after 24 h of administration of W/S emulsion. Therefore, W/S emulsions have a good in vivo residence and drug release in the vaginal mucosae showing a great potential for the treatment of sexual tissues infections, as vaginal bioadhesive delivery systems of antinfectious drugs.

Synthesis, structure, and catalytic applications for ortho- and meta-carboranyl based NBN pincer-Pd complexes.

o- and m-Carborane-based NBN pincer palladium complexes (oCB-L1)Pd, (oCB-L2)Pd, and (mCB-L1)Pd are synthesized in two steps from commercially available starting materials. The pincer complexes were prepared by the reaction of bis-[R(hydroxy)methyl]-1,2-dicarba-closo-dodecaborane (R = 2-pyridyl oCB-L1, 6-methyl-2-pyridyl oCB-L2) or bis-[2-pyridyl (hydroxy)methyl]-1,2-dicarba-meta-dodecaborane (mCB-L1) with [PdCl2(MeCN)2] under mild conditions. The X-ray structure determination of all carboranyl pincer complexes shows unambiguously B-H activation of the carborane cages. The results agree with the Pd-B bonds in all complexes exhibiting strong σ-electron donation. Theoretical calculations reveal the importance of considering the solid state intermolecular hydrogen bonding when investigating the trans influence in organometallic chemistry. A localized orbitals approach has also been applied to analyze the metal oxidation state in the carboranyl pincer complexes. Catalytic applications of (oCB-L1)Pd and (mCB-L1)Pd have shown the complexes are good catalyst precursors in Suzuki coupling in water and with very low amounts of catalyst loadings.