While remarkable progress has recently been made for the direct C−H‐functionalization of azines, its application is still limited by a lack of accessible functional groups (primarily carbon‐based) and poor regioselectivity. In contrast, C2‐functionalized pyridines and quinolines can be easily synthesized by treating readily available N‐oxides with various reagents under appropriate activation conditions. This review seeks to comprehensively document the available synthetic methods for introducing functional groups at the C2 position of pyridines and quinolines. In this work, we highlight recent developments in the C2‐functionalization of pyridine and quinoline N‐oxides and address both the mechanisms and regioselectivity of the reactions. We also describe the pathways and reactive species involved in these processes and highlight a number of medically relevant nitrogen heteroaromatics.

ObjectiveTo study the characteristics and relationship of the gut microbiota in patients with polycystic ovary syndrome (PCOS).MethodWe recruited 45 patients with PCOS and 37 healthy women from the Reproductive Department of Shengjing Hospital. We recorded their clinical indexes, and sequenced their fecal samples by 16S rDNA full-length assembly sequencing technology (16S-FAST).ResultWe found decreased α diversity and different abundances of a series of microbial species in patients with PCOS compared to healthy controls. We found LH and AMH were significantly increased in PCOS with Prevotella enterotype when compared to control women with Prevotella enterotype, while glucose and lipid metabolism level remained no significant difference, and situations were opposite in PCOS and control women with Bacteroides enterotype. Ruminococcus gnavus, Prevotella stercorea, Dialister succinatiphilus and Bacteroides fragilis were more abundant while Christensenellaceae spp. were less abundant in the PCOS group. P. stercorea was significantly more prevalent in PCOS-not insulin resistance (NIR) compared to control-NIR and PCOS-not overweight (NOW) patient groups compared to control-NOW groups. Kyoto Encyclopedia Genes and Genomes reflecting pathways related to lipopolysaccharide biosynthesis were more abundant in the PCOS group.ConclusionOur study found gut microbiota that had different abundance in patients with PCOS compared to healthy controls. An intimate relationship was shown between the gut microbiota and pathological changes in PCOS. We suggest the gut microbiota should be taken into consideration in the treatment of symptoms of PCOS via drugs and diet.

There is a famous sentence in Tao Te Ching: “The Tao produced one. One produced two. Two produced three. Three produced all things.” In this front cover picture, Tai Chi stands for Tao, and “N” and “O” in the two circles represent N‐oxides of this paper. Thunder and lightning stimulate Tai Chi to produce everything, which is represented by the five elements of metal, wood, water, fire, and earth. Therefore, this picture indicates that pyridine N‐oxides can produce numerous nitrogen‐containing heterocyclic compounds under the action of activating reagent. Details can be found in the Review by Dong Wang and co‐workers (D. Wang, L. Désaubry, G. Li, M. Huang, S. Zheng, Adv. Synth. Catal. 2021, 363, 2–39; DOI: 10.1002/adsc.202000910).

Aims The aim of this study was to systematically compare the safety and accuracy of robot-assisted (RA) technique with conventional freehand with/without fluoroscopy-assisted (CT) pedicle screw insertion for spine disease. Methods A systematic search was performed on PubMed, EMBASE, the Cochrane Library, MEDLINE, China National Knowledge Infrastructure (CNKI), and WANFANG for randomized controlled trials (RCTs) that investigated the safety and accuracy of RA compared with conventional freehand with/without fluoroscopy-assisted pedicle screw insertion for spine disease from 2012 to 2019. This meta-analysis used Mantel-Haenszel or inverse variance method with mixed-effects model for heterogeneity, calculating the odds ratio (OR), mean difference (MD), standardized mean difference (SMD), and 95% confidence intervals (CIs). The results of heterogeneity, subgroup analysis, and risk of bias were analyzed. Results Ten RCTs with 713 patients and 3,331 pedicle screws were included. Compared with CT, the accuracy rate of RA was superior in Grade A with statistical significance and Grade A + B without statistical significance. Compared with CT, the operating time of RA was longer. The difference between RA and CT was statistically significant in radiation dose. Proximal facet joint violation occurred less in RA than in CT. The postoperative Oswestry Disability Index (ODI) of RA was smaller than that of CT, and there were some interesting outcomes in our subgroup analysis. Conclusion RA technique could be viewed as an accurate and safe pedicle screw implantation method compared to CT. A robotic system equipped with optical intraoperative navigation is superior to CT in accuracy. RA pedicle screw insertion can improve accuracy and maintain stability for some challenging areas. Cite this article: Bone Joint Res 2020;9(10):653–666.

To achieve highly‐efficient organic light‐emitting diodes (OLEDs), great efforts have been devoted into constructing thermally activated delayed fluorescence (TADF) with high horizontal dipole ratios (Θ//). Here, we proposed a design strategy by integrating a rigid electron‐accepting oxygen‐bridged boron core with triple electron‐donating groups, which exhibited a “shamrock‐shape”, namely BO‐3DMAC and BO‐3DPAC. Benefiting from the rigid and large‐planar skeletons brought by shamrock‐shaped design, BO‐3DMAC and BO‐3DPAC exhibit high Θ// of 84%/70% and 93%/94% in neat/doped films, respectively, and finally furnish excellent external quantum efficiencies (EQEs) of up to 28.3% and 38.7% in 20 wt% doped OLEDs with sky‐blue emission, as well as adequate EQEs of up to 21.0% and 16.7% in nondoped OLEDs. This work unveils a promising strategy to establish high‐Θ// TADF emitters by constructing large‐planar molecular structures using shamrock‐shaped design.