[18F]fluoro-benziodoxole: a no-carrier-added electrophilic fluorinating reagent. Rapid, simple radiosynthesis, purification and application for fluorine-18 labelling

An electrophilic ¹⁸F transfer reagent was synthetized by rapid, operationally simple ligand exchange from a hypervalent iodine and [¹⁸F]TBAF.

2,2-Diiododimedone: a mild electrophilic iodinating agent for the selective synthesis of α-iodoketones from allylic alcohols

In combination with an iridium catalyst, a new electrophilic iodinating agent enables the synthesis of α-iodocarbonyls from allylic alcohols.

Efficient DBU accelerated synthesis of 18F-labelled trifluoroacetamides

Nucleophilic ¹⁸F-fluorination of bromodifluoromethyl derivatives was performed using [¹⁸F]Bu₄NF in the presence of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). This novel procedure provided a diverse set of [¹⁸F]trifluoroacetamides in good to excellent radiochemical conversions. A mechanism where DBU acts as organomediator in this transformation is proposed.

Base-Catalyzed Stereospecific Isomerization of Electron-Deficient Allylic Alcohols and Ethers through Ion-Pairing

A mild base-catalyzed strategy for the isomerization of allylic alcohols and allylic ethers has been developed. Experimental and computational investigations indicate that transition metal catalysts are not required when basic additives are present. As in the case of using transition metals under basic conditions, the isomerization catalyzed solely by base also follows a stereospecific pathway. The reaction is initiated by a rate-limiting deprotonation. Formation of an intimate ion pair between an allylic anion and the conjugate acid of the base results in efficient transfer of chirality. Through this mechanism, stereochemical information contained in the allylic alcohols is transferred to the ketone products. The stereospecific isomerization is also applicable for the first time to allylic ethers, yielding synthetically valuable enantioenriched (up to 97% ee) enol ethers.

General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand

Remarkably simple Ir^III catalysts enable the isomerization of primary and sec-allylic alcohols under very mild reaction conditions. X-ray absorption spectroscopy (XAS) and mass spectrometry (MS) studies indicate that the catalysts, with the general formula [Cp*Ir^III ], require a halide ligand for catalytic activity, but no additives or additional ligands are needed.

Highly functionalized biaryls via Suzuki-Miyaura cross-coupling catalyzed by Pd@MOF under batch and continuous flow regimes

A diverse set of more than 40 highly functionalized biaryls was synthesized successfully through the Suzuki-Miyaura cross-coupling reaction catalyzed by Pd nanoparticles supported in a functionalized mesoporous MOF (8 wt % Pd@MIL-101(Cr)-NH2 ). This could be achieved under some of the mildest conditions reported to date and a strong control over the leaching of metallic species could be maintained, despite the presence of diverse functional groups and/or several heteroatoms. Some of the targeted molecules are important intermediates in the synthesis of pharmaceuticals and we clearly exemplify the versatility of this catalytic system, which affords better yields than currently existing commercial procedures. Most importantly, Pd@MIL-101-NH2 was packed in a micro-flow reactor, which represents the first report of metallic nanoparticles supported on MOFs employed in flow chemistry for catalytic applications. A small library of 11 isolated compounds was created in a continuous experiment without replacing the catalyst, demonstrating the potential of the catalyst for large-scale applications.

Functionalising metal–organic frameworks with metal complexes: the role of structural dynamics

The impact of dynamics in the functionalisation of metal–organic framework UiO-67 with an Ir-complex has been studied. Highly functionalised Ir-UiO-67 can be only trapped as kinetic products, which lose metals and exchange species to gain stability.

Transition metal-catalyzed redox isomerization of codeine and morphine in water

A water-soluble rhodium complex formed from commercially available [Rh(COD)(CH₃CN)₂]BF₄ and 1,3,5-triaza-7-phosphaadamantane (PTA) catalyzes the isomerization of both codeine and morphine into hydrocodone and hydromorphone in water with very high efficiency.

Sustainable catalysis: rational Pd loading on MIL-101Cr-NH2 for more efficient and recyclable Suzuki-Miyaura reactions

Palladium nanoparticles have been immobilized into an amino-functionalized metal-organic framework (MOF), MIL-101Cr-NH2, to form Pd@MIL-101Cr-NH2. Four materials with different loadings of palladium have been prepared (denoted as 4-, 8-, 12-, and 16 wt%Pd@MIL-101Cr-NH2). The effects of catalyst loading and the size and distribution of the Pd nanoparticles on the catalytic performance have been studied. The catalysts were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), N2-sorption isotherms, elemental analysis, and thermogravimetric analysis (TGA). To better characterize the palladium nanoparticles and their distribution in MIL-101Cr-NH2, electron tomography was employed to reconstruct the 3D volume of 8 wt%Pd@MIL-101Cr-NH2 particles. The pair distribution functions (PDFs) of the samples were extracted from total scattering experiments using high-energy X-rays (60 keV). The catalytic activity of the four MOF materials with different loadings of palladium nanoparticles was studied in the Suzuki-Miyaura cross-coupling reaction. The best catalytic performance was obtained with the MOF that contained 8 wt% palladium nanoparticles. The metallic palladium nanoparticles were homogeneously distributed, with an average size of 2.6 nm. Excellent yields were obtained for a wide scope of substrates under remarkably mild conditions (water, aerobic conditions, room temperature, catalyst loading as low as 0.15 mol%). The material can be recycled at least 10 times without alteration of its catalytic properties.

Ten-year population-based molecular epidemiological study of tuberculosis transmission in the metropolitan area of Madrid, Spain

SETTING

The epidemiology of tuberculosis (TB) in urban populations is changing. Combining conventional epidemiological techniques with DNA fingerprinting of Mycobacterium tuberculosis can improve our understanding of how TB is transmitted.

OBJECTIVE

To improve the definition of molecular epidemiology of TB over 10 years in an area of Europe not previously studied.

DESIGN

A population-based retrospective study was conducted in the Autonomous Community of Madrid, Spain, from 1992 to 1998; from 1999 to 2001, the study was prospective. The study population consisted of all patients for whom positive culture and full clinical and demographic data were available. All strains were typed by RFLP. Non-clustered patients were compared with clustered patients and studied using univariate analysis and a logistic regression model.

RESULTS

Of 448 patients studied, 228 (50.7%) were clustered. Youth was the strongest risk factor associated with clustering. Pleural effusion was also found to be associated with clustering. An epidemiological link was found in only 85 (37.4%) of the 228 patients belonging to a cluster.

CONCLUSION

Youth and pleural effusion were identified as risk factors for clustering. These findings may help adjust TB control and contact tracing strategies.

[Morphological, histochemical and immunochemical characteristics of the terminal ileum of patients with ulcerative colitis. Relationship with the development of pouchitis]

Pouchitis is the most frequent long-term complication of the ileoanal reservoirs. Its etiology is unknown and it is currently believed to be a recurrence of ulcerative colitis in the mucosa of the ileal reservoir.

AIM

To evaluate whether the mucosa of the terminal ileum of patients with ulcerative colitis is different from that of patients free of this disease and whether there are morphological and immunological alterations which might predispose to inflammation of the reservoir.

PATIENTS AND METHODS

Colectomy samples from the terminal ileum of 20 patients (12 women, 8 men) with ulcerative colitis who had undergone restorative proctocolectomy with ileoanal reservoir and of 10 controls who had undergone right hemicolectomy for other causes were studied. During follow-up (46.9 months) seven patients were diagnosed with pouchitis (Sandborn > 7). In all patients, morphometric histopathologic, histochemical and immunohistochemical studies of the ileal mucosa were performed.

RESULTS

Chronic inflammatory infiltrate and the degree of villous atrophy and of global chronic inflammation were significantly higher in the terminal ileum of patients with ulcerative colitis than in the control group. There were no differences in the mucin content between the two groups and IgA, IgG and B lymphocyte expression was significantly higher in the terminal ileum of patients with ulcerative colitis. Chronic inflammatory infiltrate, degree of atrophy, villous atrophy and of global chronic infiltration, macrophage and CD8 lymphocyte expression were higher in the terminal ileum of patients with pouchitis, but differences was not significant.

CONCLUSIONS

The terminal ileum of patients with ulcerative colitis has histopathologic, morphometric and immunohistochemical characteristics that are different from those of patients without this disease. These results may eventually lead to an association between alterations in the ileum and the subsequent development of pouchitis.