Cobalt-Catalyzed Domino Transformations via Enantioselective C-H Activation/Nucleophilic [3 + 2] Annulation toward Chiral Bridged Bicycles

Selective synthesis of chiral bridged (hetero)bicyclic scaffolds via asymmetric C-H activation constitutes substantial challenges due to the multiple reactivities of strained bicyclic structures. Herein, we develop the domino transformations through an unprecedented cobalt-catalyzed enantioselective C-H activation/nucleophilic [3 + 2] annulation with symmetrical bicyclic alkenes. The methods offer straightforward access to a wide range of chiral molecules bearing [2.2.1]-bridged bicyclic cores with four and five consecutive stereocenters in a single step. Two elaborate salicyloxazoline (Salox) ligands were synthesized based on the rational design and mechanistic understanding. The well-defined chiral pockets generated from asymmetric coordination around the trivalent cobalt catalyst direct the orientation of bicyclic alkenes, leading to excellent enantioselectivity.

Cobalt-Catalyzed Enantioselective C-H Carbonylation towards Chiral Isoindolinones

Transition metal-catalyzed enantioselective C-H carbonylation with carbon monoxide, an essential and easily available C1 feedstock, remains challenging. Here, we disclosed an unprecedented enantioselective C-H carbonylation catalyzed by inexpensive and readily available cobalt(II) salt. The reactions proceed efficiently through desymmetrization, kinetic resolution, and parallel kinetic resolution, affording a broad range of chiral isoindolinones in good yields with excellent enantioselectivities (up to 92 % yield and 99 % ee). The synthetic potential of this method was demonstrated by asymmetric synthesis of biological active compounds, such as (S)-PD172938 and (S)-Pazinaclone. The resulting chiral isoindolinones also serve as chiral ligands in cobalt-catalyzed enantioselective C-H annulation with alkynes to construct phosphorus stereocenter.

Cobalt-Catalyzed Enantioselective C-H Annulation of Benzylamines with Alkynes: Application to the Modular and Asymmetric Syntheses of Bioactive Molecules

The transition metal-catalyzed enantioselective C-H functionalization strategy has revolutionized the logic of natural product synthesis. However, previous applications have heavily relied on the use of noble metal catalysts such as rhodium and palladium. Herein, we report the efficient synthesis of C1-chiral 1,2-dihydroisoquinolines (DHIQs) via enantioselective C-H/N-H annulation of picolinamides with alkynes catalyzed by a more sustainable and cheaper 3d metal catalyst, cobalt(II) acetate tetrahydrate. A wide range of enantiomerically enriched DHIQs were obtained in good yields with excellent enantioselectivities (up to 98% yield and >99% ee). The robustness and synthetic potential of this method were demonstrated by the modular and asymmetric syntheses of several tetrahydroisoquinoline alkaloids, including (S)-norlaudanosine, (S)-laudanosine, (S)-xylopinine, (S)-sebiferine, and (S)-cryptostyline II, and the asymmetric syntheses of key intermediates of (+)-solifenacin, FR115427, and (+)-NPS R-568.

Synthesis of Axially Chiral Biaryls through Cobalt(II)-Catalyzed Atroposelective C-H Arylation

Highly efficient synthesis of axially chiral biaryl amines through cobalt-catalyzed atroposelective C-H arylation using easily accessible cobalt(II) salt and salicyloxazoline ligand has been reported. This methodology provides a straightforward and sustainable access to a broad range of enantioenriched biaryl-2-amines in good yields (up to 99 %) with excellent enantioselectivities (up to 99 % ee). The synthetic utility of the unprecedented method is highlighted by its scalability and diverse transformations.

Base-Promoted Electrochemical Co(II)-catalyzed Enantioselective C-H Oxygenation

Metalla-electrocatalyzed C-H oxygenation represents one of the most straightforward and sustainable approaches to access valuable oxygenated molecules. Despite the significant advances, the development of enantioselective electrochemical C-H oxygenation reaction is very challenging and remains elusive. Herein, we described the first electrochemical Co(II)-catalyzed enantioselective C-H alkoxylation. A broad range of enantioenriched alkoxylated phosphinamides were obtained in good yields with excellent enantioselectivities (up to 98% yield and >99% ee). An unusual cobalt(III) alcohol complex was prepared and fully characterized, which was proved to be a key intermediate of this C-H alkoxylation reaction. Mechanistic studies revealed that the oxidation of Co(III) to Co(IV) was facilitated by a base and the whole process proceeded through a cobalt(III/IV/II) catalytic cycle.

Enantio- and Regioselective Electrooxidative Cobalt-Catalyzed C-H/N-H Annulation with Alkenes

In recent years, the merging of electrosynthesis with 3d metal catalyzed C-H activation has emerged as a sustainable and powerful technique in organic synthesis. Despite the impressive advantages, the development of an enantioselective version remains elusive and poses a daunting challenge. Herein, we report the first electrooxidative cobalt-catalyzed enantio- and regioselective C-H/N-H annulation with olefins using an undivided cell at room temperature (up to 99 % ee). ^t Bu-Salox, a rationally designed Salox ligand bearing a bulky tert-butyl group at the ortho-position of phenol, was found to be crucial for this asymmetric annulation reaction. A strong cooperative effect between ^t Bu-Salox and 3,4,5-trichloropyridine enabled the highly enantio- and regioselective C-H annulation with the more challenging α-olefins without secondary bond interactions (up to 96 % ee and 97 : 3 rr). Cyclovoltametric studies, and the preparation, characterization, and transformation of cobaltacycle intermediates shed light on the mechanism of this reaction.

Cobalt/Salox-Catalyzed Enantioselective C-H Functionalization of Arylphosphinamides

Previous methods on Co^III -catalyzed asymmetric C-H activation rely on the use of tailor-made cyclopentadienyl-ligated Co^III complexes, which require lengthy steps for the preparation. Herein, we report an unprecedented enantioselective C-H functionalization enabled by a simple cobalt/salicyloxazoline (Salox) catalysis. The chiral Salox ligands can be easily prepared in one step from salicylonitrile and chiral amino alcohols. A broad range of P-stereogenic compounds were synthesized in high yields with excellent enantioselectivities (45 examples, up to 99 % yield and >99 % ee). The isolation and characterization of several intermediates provided insights into the generation of active catalytic cobalt species, the action of Salox, and the mode of stereocontrol.

Cobalt-Catalyzed Oxidative [4+2] Annulation of Benzamides with Dihydrofuran: A Facile Route to Tetrahydrofuro[2,3-c]isoquinolinones

A cobalt-catalyzed oxidative [4+2] annulation of benz­amides with dihydrofuran was developed for the expeditious synthesis of tetrahydrofuro[2,3-c]isoquinolinones. Commercially available and inexpensive Co(OAc)2·4H2O was used as an efficient catalyst. Various functional groups were tolerated, affording the desired products in good yields with excellent regioselectivity and good diastereoselectivity under mild conditions.

[SERPINE2 promotes cellular migration and invasion in esophageal squamous cell carcinoma by activating β-catenin]

Objective: To clarify the function and molecular mechanisms of serpin family E member 2 (SERPINE2) in cellular migration and invasion of esophageal squamous cell carcinoma (ESCC). Methods: The expression of SERPINE2 in ESCC was analyzed by using online databases TCGA (http: //gepia.cancer-pku.cn/detail.php and http: //ualcan.path.uab. edu/index.html). The expressions of SERPINE2 mRNA in normal human esophageal epithelial cell line NE2, human ESCC cell lines KYSE30 and KYSE150 were detected by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). SERPINE2-konckdown or SERPINE2-overexpressed plasmid was transfected into KYSE30 cells, and the efficiencies of the knockdown and overexpression system were tested by qRT-PCR. The relationships of SERPINE2 and ESCC migration and invasion were determined by migration and invasion assays in vitro. The associations between SERPINE2 expression and β-catenin as well as its target genes including c-Myc, cyclin D1 and CD44 were analyzed by immunofluorescence, qRT-PCR and western blot, respectively. Results: The expressions of SERPINE2 were significantly upregulated in both esophageal cancer (ESCA) and ESCC tissues compared to normal tissues by analyzing 182 and 95 cases, respectively (P<0.01). SERPINE2 is highly expressed in both KYSE30 and KYSE150 cells (P<0.05). The number of migrating and invading cells in control group were (212.66±24.11)/field and (136.00±14.42)/field, while were (88.33±9.71)/field and (77.00±9.53)/field in SERPINE2-knockdown 1 group, and (66.00±8.00)/field and (45.66±3.78)/field in SERPINE2-knockdown 2 group, respectively, and the differences were dramatically significant compared with the control group (P<0.01). The number of migrating and invading cells in control group were (250.00±30.00)/field and (203.33±15.27)/field, while were (383.33±35.11)/field and (246.66±25.16)/field in SERPINE2-overpressed group, and the differences were strikingly significant compared with the control group (P<0.01). The protein expression of β-catenin was upregulated while phosphorylated β-catenin protein expression was downregulated in SERPINE2-overexpressed KYSE30 cells when compared to control cells.The transcription activity of β-catenin was significantly upregulated and the mRNA expressions of its target genes including c-Myc, cyclin D1 and CD44 were all increased. After treated with 25 μM iCRT14, the number of migrated cells in the control and SERPINE2-overpressed groups were (200.00±36.05)/field and (258.33±22.54)/field, and the number of invaded cells were (160.00±17.32)/field and (188.33±25.65)/field, respectively, the differences were dramatically significant compared with the group without iCRT14 treatment (P<0.01). Conclusion: SERPINE2 is significantly upregulated in ESCC cells and can promote cellular migration and invasion by activating β-catenin, which may provide a potential therapeutic target for patients with ESCC.

Duration of feeding linseed diet influences expression of inflammation-related genes and growth performance of growing-finishing barrows

The aim of the study was to investigate the effects of dietary linseed (rich in n-3 PUFA) on expression of inflammation-related genes and on growth performance of growing-finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, one as the basal diet and the other containing 10% linseed. Twenty-four Landrace x Yorkshire barrows weighing 35 +/- 3.7 kg were randomly assigned to 1 of 4 treatment groups, with 6 pigs per group. During the entire experimental period of 90 d, these 4 groups of pigs were first fed the basal diet and then fed the linseed diet for 0, 30, 60, and 90 d before slaughter, respectively. Pig growth; messenger RNA (mRNA) expression of peroxisome proliferator-activated receptor-gamma (PPARgamma), IL-1beta0, IL-6, and tumor necrosis factor-alpha (TNF-alpha); and plasma concentrations of the 3 proinflammatory cytokines were measured and analyzed. Average daily feed intake did not differ among treatment groups (P > 0.05), but ADG (P < 0.05) and G:F (P < 0.01) responded quadratically to the duration of linseed diet feeding, and pigs in the 60-d treatment group had the greatest ADG and G:F. The mRNA expression of PPARgamma in loin muscle and spleen increased linearly (P < 0.01) with the duration of linseed diet feeding, whereas its expression in adipose tissue was not affected (P = 0.095). Tumor necrosis factor-alpha and IL-6 mRNA expression in muscle, adipose, and spleen, as well as serum concentration of TNF-alpha, decreased linearly (P < 0.01) with the duration of linseed diet feeding. Peroxisome proliferator-activated receptor-gamma mRNA abundance was negatively correlated with IL-1beta, IL-6, and TNF-alpha mRNA abundance both in muscle (R(2) = 0.63, P < 0.001) and in spleen (R(2) = 0.69, P < 0.001), and PPARgamma mRNA expression in spleen (R(2) = 0.59, P < 0.01) and muscle (R(2) = 0.52, P < 0.05) was negatively correlated with serum TNF-alpha concentration. There were also significant quadratic relations between ADG and expression of PPARgamma (P < 0.05) and splenic TNF-alpha (P < 0.05). These data suggest that intake of n-3 PUFA from the linseed diet led to significant decreases in the expression of proinflammatory cytokine genes, which may stimulate growth in growing-finishing barrows, at least in part, through a PPARgamma-dependent mechanism.

Transvaginal ultrasound-guided aspiration and surgical starch sclerosis therapy in recurrent pelvic inclusion cysts--report of two cases

Pelvic inclusion cyst is one of the complications of major abdominal surgery. Treatment of the symptomatic mass is either surgical or needle aspiration. However, recurrence of the condition is still not uncommon. Repeated surgery or aspiration could result in serious morbidity. We report two cases of recurrent pelvic inclusion cyst which were successfully treated with transvaginal aspiration and sclerosing therapy with starch powder from surgical gloves and normal saline solution. The aspirations were guided by transvaginal ultrasound and on local paracervical anesthesia. Starch and normal saline solution were injected through the aspiration needle for irrigation three times. One patient with a large cyst needed two treatment courses, the other only one. Both patients had no discomfort both intra- and postoperatively. A Follow-up ultrasonography proved no recurrence to date.