Dinuclear gold-catalyzed divergent dechlorinative radical borylation of gem-dichloroalkanes.

The enormous and widespread use of organoboronic acids has prompted the development of innovative synthetic methodologies to meet the demands on structural diversity and functional group tolerance. The existing photoinduced defunctionalization radical borylation, typically focused on the conversion of one C-X bond (X= Br, I, or other leaving group) into only one C-B bond. Herein, we disclose a divergent radical dechloroborylation reaction enabled by dinuclear gold catalysis with visible light irradiation. A wide range of structurally diverse alkyl boronic, α-chloroboronic, and gem-diboronic esters can be synthesized in moderate to good yields (up to 92%). Its synthetic robustness is further demonstrated on a preparative scale and applied to late-stage diversification of complex molecules. The process hinges on a C-Cl bond relay activation in readily available gem-dichloroalkanes through inner-sphere electron transfer, overcoming the redox potential limits of unreactive alkyl chlorides.

Photoinduced activation of alkyl chlorides.

In recent years, the activation of unactivated alkyl chlorides through light-induced processes has emerged as a promising field in radical chemistry, and has led to new transformations in organic synthesis. Direct utilization of alkyl chlorides as C(sp3)-hybridized electrophiles enables the facile construction of carbon-carbon and carbon-heteroatom bonds. Furthermore, recent studies in medicinal chemistry indicate that their presence is associated with high levels of success in clinical trials. This review summarizes the recent advances in the photoinduced activation of unactivated alkyl chlorides and discusses the mechanistic aspects underlying these reactions. We anticipate that this review will serve as a valuable resource for researchers in the field of unactivated chemical bond functionalization, and inspire considerable developments in organic chemistry, drug synthesis, materials science and other related disciplines.

Dinuclear-gold-catalyzed cyclization of 1,7-enynes with alkyl bromides.

Dinuclear-gold-catalyzed radical difunctionalization of alkyl bromides with 1,7-enynes has been established via dehalogenation and 1,5-HAT processes. This protocol was used to construct, in a facile and efficient manner, a wide range of cyclopenta[c]quinolines bearing two quaternary carbon centers with good yields (28 examples, up to 84% yield). The good functional group compatibility and gram-scale preparation ability of the reaction proved its synthetic robustness.

Anterior controllable antedisplacement and fusion: quantitative analysis of a single surgeon's learning experience.

BACKGROUND CONTEXT: Anterior controllable antedisplacement and fusion (ACAF) is a novel surgical technique for the treatment of ossification of the posterior longitudinal ligament (OPLL) but the surgical learning curve for this technique has not been previously characterized. PURPOSE: The aim of this study was to quantify a surgeon's learning curve for ACAF and the effect of surgeon experience on postoperative outcomes. STUDY DESIGN: Prospective study of a single institution and single surgeon experience with ACAF surgery. PATIENT SAMPLE: A total of 70 consecutive patients with OPLL undergoing ACAF surgery by a single, non-ACAF trained surgeon between 2017 and 2020 were analyzed. OUTCOME MEASURES: Intraoperative and postoperative outcomes (blood loss, operative time, errors of surgical procedure, length of hospital stay, Japanese Orthopedic Association (JOA) scoring system, and surgical complications) were assessed. METHODS: We prospectively reviewed the first 70 ACAF procedures between 2017 and 2020 performed by a single, non-ACAF trained surgeon. The function relationship between the operative time and case number was fitted using a locally weighted scatterplot smoothing (LOESS) plot. Spearman's correlation analysis was performed to determine factors affecting the operative time. The operative time-related learning curve for ACAF was established and difficulty of each procedure was assessed using a cumulative sum (CUSUM) model. The association between the specific errors of surgical procedures and surgeon experience was further analyzed. A modified CUSUM model was also used to establish the surgical procedure-related learning curve, and thus whether these two learning curves matched with each other was observed. Postoperative outcomes in relation to surgeon experience was compared using a Wilcoxon rank sum test and Chi-squared test. RESULTS: Operative time presented a specific pattern of fewer patient-dependent changes as the case number increased. Spearman's correlation analysis showed the operative time was more affected by the case number (r=-0.73) than the complexity of condition and number of levels hoisted. The operative time-related CUSUM model identified the early (first 29 cases) and late phase (late 41 cases) of the learning process, which was also confirmed by a modified CUSUM model based on surgical procedure. The critical point of the CUSUM model for bilateral osteotomies was at case number 29, and time reduction after the early phase was approximately 34 minutes. Length of hospital stay and blood loss were less during the late phase than during the early phase (p<.05). Although no significant difference was observed in postoperative JOA scores between two phases, patients in the late phase obtained higher recovery rates of neurologic function than those in the early phase (p<.01). There was significant difference in the number of specific errors between the two phases (p=.02). There were no significant differences in overall complication rates between two phases, but a higher incidence of certain complications caused by specific errors was observed in the early phase (p=.02), including CSF leakage, C5 palsy and incomplete decompression. CONCLUSIONS: We described, for the first time, a detailed learning curve for ACAF surgery. About 29 cases were needed to achieve mastery of ACAF. Once mastered, the surgeon could deal with various OPLL presentations in a universal way regardless of condition complexity and number of surgical levels. Bilateral osteotomies were the most difficult part of ACAF and produced the greatest reduction in time after mastery. We found a close association between specific errors of surgical procedure for ACAF and surgeon experience. Furthermore, certain complications caused by these errors should be on the alert during the early phase of learning ACAF, including CSF leakage, C5 palsy and incomplete decompression.

The clinical value of three-dimensional measurement in the diagnosis of thoracic myelopathy caused by ossification of the ligamentum flavum.

BACKGROUND: Thoracic ossification of the ligamentum flavum (OLF) is a major cause of thoracic myelopathy, which is often accompanied by multiple segmental stenosis or other degenerative spinal diseases. However, in the above situations, it is difficult to determine the exact segment responsible. The objective of this study was to analyze three-dimensional (3D) radiological parameters in order to establish a novel diagnostic method for discriminating the responsible segment in OLF-induced thoracic myelopathy, and to evaluate its superiority compared to the conventional diagnostic methods. METHODS: Eighty-one patients who underwent surgery for thoracic myelopathy caused by OLF from 2016 to 2020 were enrolled in this study as the myelopathy group, and 79 patients who had thoracic OLF but displayed no definite neurological signs from 2018 to 2020 were enrolled as the non-myelopathy group. We measured the one-dimensional (1D), two-dimensional (2D), and 3D radiological parameters, calculated their optimal cutoff values, and compared their diagnostic values. RESULTS: Significant differences were observed in the 1D, 2D, and 3D radiological parameters between the myelopathy and non-myelopathy groups (P<0.01). As a 3D radiological parameter, the OLF volume (OLFV) ratio (OLFV ratio = OLFV/normal canal volume × 100%) was the most accurate parameter for diagnosing OLF-induced thoracic myelopathy, with a diagnostic coincidence rate of 88.1%. We also found that an OLFV ratio of 26.3% could be used as the optimal cutoff value, with a sensitivity of 87.7% and a specificity of 88.6%. Moreover, the OLFV ratio [area under the curve (AUC): 0.92, 95% confidence interval (CI): 0.86-0.95] showed a statistically higher diagnostic value than the 1D and 2D parameters (AUC: 0.75, 95% CI: 0.67-0.81; AUC: 0.84, 95% CI: 0.77-0.89, respectively) (P<0.05). Pearson correlation analysis illustrated that the OLFV ratio was significantly negatively correlated with preoperative modified Japanese Orthopedic Association (mJOA) score (r=-0.73, 95% CI: -0.81 to -0.60, P<0.01). CONCLUSIONS: Our results demonstrate the superiority of the OLFV ratio over the conventional 1D and 2D computed tomography (CT)-based radiological parameters for the diagnosis of OLF-induced thoracic myelopathy. The novel diagnostic method based on the OLFV ratio will help to determine the responsible segment in multi-segmental thoracic OLF or when thoracic OLF coexists with other degenerative spinal diseases. The OLFV ratio also accurately reflects the clinical state of symptomatic patients with thoracic OLF.

[Biocontrol effect and mechanism of Bacillus laterosporus Bl13 against early blight disease of tomato]. / 侧孢芽孢杆菌Bl13å¯¹ç•ªèŒ„æ—©ç–«ç— é˜²æ²»æ•ˆæžœåŠæœºåˆ¶.

Bacillus laterosporus Bl13 has good antagonistic effect on the pathogen of tomato early blight (TEB) disease. A pot experiment was conducted to investigate the effect and mechanism of B. laterosporus Bl13 against TEB disease by measuring biological traits such as plant height, stem diameter, disease index of TEB, activity of plant defense enzyme in leaves, and microbial diversity and community composition in root area. The results showed that B. laterosporus Bl13 could significantly reduce the disease index of TEB disease incidence, increase the activity of defensive enzymes including polyphenol oxidase (PPO) and peroxidase (POD) in leaves, and reduce the effects of the disease on the aboveground and root growth of tomato. Meanwhile, B. laterosporus Bl13 improved soil microbial community structure in the root zone, by significantly increasing the relative abundance of plant growth-promoting bacteria (Bacillus and Pseudomonas) and decreasing that of Olpidium and Haematonectria. The results showed that B. laterosporus Bl13 could enhance plant resistance against TEB disease through improving the activity of defensive enzymes in tomato leaves and increasing the number of beneficial microbes in the root zone.

Dinuclear gold catalysis.

Gold chemistry has developed extensively in the past decade, and a dozen good reviews have been presented discussing this progress. Few however have paid close attention to the progress in organic synthesis of dinuclear gold-catalysis. A dinuclear gold catalyst is defined here as a gold complex with two gold centers linked by a bidentate ligand. With theoretical analysis and some representative studies in recent years, this comprehensive review highlights the particular properties of dinuclear gold-complexes, especially aurophilic interactions, and systematically summarizes the recent achievements of dinuclear gold-catalyzed coupling reactions, asymmetric catalysis, and photocatalysis, where dinuclear gold catalysts tend to show a greater advantage than the mononuclear gold catalysts.

Catalytic Three-Component Synthesis of Functionalized Naphtho[2,1-b]oxecines via a Double Bond Cleavage-Rearrangement Cascade.

A new double annulation cascade involving a [2 + 2] cycloaddition-retroelectrocyclization (CA-RE) process was first reported, leading to the generation of unprecedented dibenzoannulated naphtho[2,1-b]oxecines with good to excellent yields and high stereoselectivity through catalytic scission/recombination of C-C double bonds under the mild conditions. An Y(OTf)3-catalyzed three-component reaction of α-alkynyl naphthalen-2-ols with ß,γ-unsaturated α-ketoesters enabled direct ring expansion of the naphthalene ring and carbon-carbon double bond cleavage/rearrangement of α-ketoesters to give macrocyclic architectures.

High-coordinate CoII and FeII compounds constructed from an asymmetric tetradentate ligand show slow magnetic relaxation behavior.

Using an asymmetric tetradentate ligand N-((6-(1H-pyrazol-1-yl)pyridin-2-yl)methylene)benzohydrazide (pypzbeyz), two high-coordinate 3d transition metal compounds [CoII(pypzbeyz)(NO3)2] (1) and [FeII(pypzbeyz)2](BF4)2(CH3CN) (2) have been synthesized and characterized by structural and magnetic measurements. X-ray crystallographic analyses revealed that compound 1 is seven-coordinate with a distorted pentagonal bipyramidal geometry (pseudo-D5h) and compound 2 is eight-coordinate with a triangular dodecahedral geometry (pseudo-D2d). Direct current (dc) magnetic susceptibilities revealed that compound 1 shows easy-plane magnetic anisotropy (D = +29.9 cm-1, E = 0.31 cm-1) and 2 shows easy-axis magnetic anisotropy (D = -6.6 cm-1, E = 0.02 cm-1). Alternating current (ac) magnetic measurements indicate that both compounds exhibit field-induced slow magnetic relaxation behavior. Furthermore, ab initio calculations also demonstrate that compound 1 presents a strong easy-plane magnetic anisotropy and 2 presents an easy-axis magnetic anisotropy, which are further identified by the calculated orientations of the local magnetic axes. These results demonstrate an effective way to achieve the targeted synthesis of high-coordinate 3d SIMs.