Nickel complexes have been widely employed as catalysts in C-C and C-heteroatom bond formation reactions. In addition to Ni(0) and Ni(II) intermediates, several Ni-catalyzed reactions are proposed to also involve odd-electron Ni(I) and Ni(III) oxidation states. We report herein the isolation, structural and spectroscopic characterization, and organometallic reactivity of Ni(III) complexes containing aryl and alkyl ligands. These Ni(III) species undergo transmetalation and/or reductive elimination reactions to form new C-C or C-heteroatom bonds and are also competent catalysts for Kumada and Negishi cross-coupling reactions. Overall, these results provide strong evidence for the direct involvement of organometallic Ni(III) species in cross-coupling reactions and oxidatively induced C-heteroatom bond formation reactions.

Nickel-catalyzed cross-coupling reactions are experiencing a dramatic resurgence in recent years given their ability to employ a wider range of electrophiles as well as promote stereospecific or stereoselective transformations. In contrast to the extensively studied Pd catalysts that generally employ diamagnetic intermediates, Ni systems can more easily access various oxidation states including odd-electron configurations. For example, organometallic Ni intermediates with aryl and/or alkyl ligands are commonly proposed as the active intermediates in cross-coupling reactions. Herein, we report the first isolated Ni-dialkyl complex and show that this species is involved in stoichiometric and catalytic C-C bond formation reactions. Interestingly, the rate of C-C bond formation from a Ni center is enhanced in the presence of an oxidant, suggesting the involvement of transient Ni species. Indeed, such a Ni species was observed and characterized spectroscopically for a nickelacycle system. Overall, these studies suggest that both Ni and Ni species could play an important role in a range of Ni-catalyzed cross-coupling reactions, especially those involving alkyl substrates.

A very convenient one-step synthesis to cross-linked polymeric nanoparticles by conventional radical copolymerization without the addition of stabilizers or surfactants was explored. Moreover, these nanoparticles exhibited excellent stability, activity and selectivity in the cycloaddition reaction of CO(2) to epoxides and could be separated from the products easily and reused.

Background Mycoplasma genitalium (MG) is one of the common causes of non-gonococcal urethritis (NGU) in men and is associated with cervicitis, endometritis, and pelvic inflammatory diseases (PID) in women. The prevalence of MG infection has been reported to be high among female sex workers (FSWs) in many countries, but limited information is known among this population in China. Methods From July to September 2009, venue-based FSWs were recruited in two cities (Wuzhou and Hezhou) of Guangxi Autonomous Region in southwest China. Information of socio-demographic and behavioral characteristics was collected by a questionnaire-based interview. Cervical specimens were obtained for detection of MG using a real-time polymerase chain reaction (PCR) assay targeting mgpA gene. Results The overall prevalence of MG infection among 810 FSWs was 13.2% (95% CI = 10.87%–15.52%). MG infection was significantly associated with less education (adjusted odds ratio (AOR) = 2.36, 95% CI = 1.15–4.87) consisting of junior high school or below, being single (AOR = 2.27, 95% CI = 1.42–3.62), migrant background (AOR = 2.03, 95% CI = 1.29–3.20), and absence of any STI symptoms in the previous year (AOR = 1.66, 95% CI = 1.09–2.52). Conclusions MG infection was prevalent among FSWs in the study areas. This pattern of infection suggests that an increasing attention should be paid to MG screening and treatment in this high risk population.

BackgroundAlthough Mycoplasma genitalium (MG) is a common sexually transmitted infection (STI), very little information regarding the prevalence of MG among MSM (men who have sex with men) is available in China. The objective of this study was to determine the prevalence of MG among MSM in the city of Shenzhen, Guangdong Province, China, and to identify the potential risk factors associated with MG infection in this population.MethodsBetween January and May 2010, a total of 409 MSM were recruited in Shenzhen, Guangdong Province, China. An anonymous questionnaire was used to collect information regarding their sociological and sexual behaviors. In addition, their first-void urine (FVU) samples and rectal swabs were collected for PCR-based MG testing.ResultsAmong the 406 FVU and 405 rectal swab samples were collected from 409 MSM, the overall MG prevalence was 8.1% (33/406, 95% CI 5.7%-10.6%), with a FVU positivity of 3.4% (95% CI 1.7%-5.4%) and a rectal positivity of 5.4% (95% CI 3.5%-7.7%). Using both univariate and multivariable logistic regression analyses, urethral MG infection was significantly associated with having more heterosexual behaviors (AOR 7.16, 95% CI 1.89-27.13), and with having unprotected anal intercourse in the past six months (AOR 4.80, 95% CI 1.40-16.47). Rectal MG infection was significantly associated with HIV infection based on univariate logistic regression analysis (OR = 4.49, 95% CI 1.18-17.12).ConclusionsIn this study, we investigated the prevalence of MG infection in the population of interest, as determined from both urethral and rectal specimen. We showed that MG was more prevalent in MSM who had bisexual behaviors compared to those who engaged only in homosexual behaviors. Further work is needed to establish the mode of MG transmission and to identify its role in HIV transmission. Meanwhile, more attention should be paid to MG infection among MSMs, and especially bisexual MSMs, which might have critical implications for effective HIV/STD control in China.

High-throughput analyses of multitarget markers can facilitate rapid and accurate clinical diagnosis. Suspension array assays, a flow cytometry-based analysis technology, are among some of the most promising multicomponent analysis methods for clinical diagnostics and research purposes. These assays are appropriate for examining low-volume, complex samples having trace amounts of analytes due to superior elimination of background. Physical shape is an important and promising code system, which uses a set of visually distinct patterns to identify different assay particles. Here, we presented a morphology recognizable suspension arrays based on the microorganisms with different morphologies. In this study, UiO-66-NH2 (UiO stands for University of Oslo) metal–organic frameworks (MOFs), was wrapped on the microorganism surface to form an innovative class of microorganism@UiO-66-NH2 composites for suspension array assays. The use of microorganisms endowed composites barcoding ability with their different morphology and size. Meanwhile, the UiO-66-NH2 provided a stable rigid shell, large specific surface area, and metal­(IV) ions with multiple binding sites, which could simplify the protein immobilization procedure and enhance detection sensitivity. With this method, simultaneous detection of three colorectal cancer-related microRNA (miRNA), including miRNA-21, miRNA-17, and miRNA-182, could be easily achieved with femtomolar sensitivity by using a commercial flow cytometer. The synergy between microorganisms and MOFs make the composites a prospective barcoding candidate with excellent characteristics for multicomponent analysis, offering great potential for the development of high throughput and accurate diagnostics.

A series of chiral squaramides were employed in the oxa‐Michael‐aza‐Henry cascade reaction of 2‐hydroxyaryl‐substituted α‐amido sulfones and nitroolefins. In the presence of 10 mol % of a squaramide catalyst and K2CO3 (aq) in CHCl3 at 0 °C, this reaction proceeded smoothly to afford chiral multisubstituted 4‐amino‐3‐nitrobenzopyrans, bearing a readily removable N‐Boc protecting group (Boc=tert‐butoxycarbonyl), in excellent yields (up to 98 %) and enantioselectivity [up to 98:2 enantiomeric ratio (er) and 93:7 diastereomeric ratio (dr)]. The 4‐amino‐3‐nitrobenzopyrans were converted into chiral 3,4‐diamino chromanes, which were further exploited as chiral ligands in the asymmetric transfer hydrogenation of acetophenone, providing 1‐phenylethanol in up to 84 % yield and 93.5:6.5 er.

A series of multifunctional catalysts with two chiral diaminocyclohexane units were developed and successfully applied in the asymmetric oxa-Michael-aza-Henry cascade reaction of salicylaldimines with nitroolefins. This approach provides a simple and efficient entry to polysubstituted chiral 4-aminobenzopyrans with three consecutive stereocenters and in high yield (up to 97%) with excellent stereoselectivity (up to 98% ee and >99:1 dr). Facile access to the nonsymmetric optically pure 3,4-diaminochromanes was also obtained.