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The Journal of Organic Chemistry Jul 2024An efficient [3 + 2] cycloaddition reaction between generated nitrile imines from hydrazonoyl halides and vinylsulfonium salts is developed. The nitrile imines are...
An efficient [3 + 2] cycloaddition reaction between generated nitrile imines from hydrazonoyl halides and vinylsulfonium salts is developed. The nitrile imines are demonstrated to be a new class of reaction partner for vinylsulfonium salts to conduct the [3 + 2] cycloaddition reaction. The process provides a concise and efficient method for the construction of pyrazole derivatives under mild reaction conditions with broad substrate scope, good product yields, and high regioselectivity.
PubMed: 38953547
DOI: 10.1021/acs.joc.4c00910 -
Accounts of Chemical Research Jul 2024ConspectusThe halogen-metal exchange reaction is a very powerful method for preparing functionalized organometallic reagents in the fields of organic and organometallic...
ConspectusThe halogen-metal exchange reaction is a very powerful method for preparing functionalized organometallic reagents in the fields of organic and organometallic chemistry. Since its inception, significant interest has been directed toward the on-demand development of new halogen-metal exchange reactions, primarily through the upgrading of exchange reagents. The enduring quest for optimal reactivity, superior functional group compatibility, and innovative synthetic applications of exchange reagents remains a fundamental objective. In the past several years, the emergence of some significant discoveries in halogen-metal exchange reactions has proclaimed a renaissance to this field. This Account outlines the latest advances within the domain contributed by the Knochel group, including the main points as follows.The stereoretentive I/Li exchange on stereodefined secondary alkyl iodides was developed for the synthesis of nonstabilized chiral secondary alkyllithium reagents. This provided a straightforward method to access chiral organolithium reagents, which can be trapped by various electrophiles or transmetalated with other metals such as copper, zinc, and magnesium, thus enabling the stereoselective synthesis of a series of functionalized compounds and natural products.Faster halogen-magnesium and halogen-zinc exchanges in toluene were realized using a novel kind of exchange reagent complexed with lithium alkoxide. These highly efficient exchange reactions are much faster than traditional ones and performed in an industrially friendly solvent. These advantages are of great value in practical synthesis, paving the way for new developments in this evolving area.Halogen-lanthanide exchanges and their novel applications in organic synthesis were established. These new exchanges introduced the lanthanide metals into halogen-metal exchange reactions for the first time, thereby opening new avenues in synthetic chemistry. Building on these achievements, a comparative analysis of the exchange reaction rates by kinetic study has quantified the relationship between the electronegativity of metals and the rates of halogen-metal exchanges.Br/Na exchange in continuous flow was achieved using a hexane-soluble exchange reagent, 2-ethylhexylsodium. This approach effectively circumvented the poor solubility of the organosodium reagent, which has proven to be of significant practical value and greatly enhanced the synthetic utility of the organosodium reagent in organic synthesis.These remarkable breakthroughs as mentioned above are fueled mainly by upgrading the exchange reagents, resulting in the development of new halogen-metal exchange reactions and innovative applications in organic synthesis. Given the importance of halogen-metal exchanges in synthetic chemistry, the pursuit of other types of exchange reactions, particularly those involving new metals, will be in continuous demand. This Account provides a timely summary of recent progress and will undoubtedly inspire further advances to drive this research field forward.
PubMed: 38953535
DOI: 10.1021/acs.accounts.4c00242 -
Journal of Biochemical and Molecular... Jul 2024Cyclophosphamide (CP) is an antineoplastic drug widely used in chemotherapy. Curcumin (CUR) and piperine (PP) show a protective effect on neurodegenerative and...
Cyclophosphamide (CP) is an antineoplastic drug widely used in chemotherapy. Curcumin (CUR) and piperine (PP) show a protective effect on neurodegenerative and neurological diseases. This research was designed to measure several biochemical parameters in the brain tissue of CP-applied rats to investigate the impact of combined CUR-PP administration. The study evaluated six groups of eight rats: Group 1 was the control; Groups 2 and 3 were administered 200 or 300 mg/kg CUR-PP via oral gavage; Group 4 received only 200 mg/kg CP on day 1; Groups 5 and 6 received CP + CUR-PP for 7 days. Data from all parameters indicated that CP caused brain damage. Phosphorylated TAU (pTAU), amyloid-beta peptide 1-42 (Aβ1-42), glutamate (GLU), and gamma amino butyric acid (GABA) parameters were the same in Groups 4, 5, and 6. On the other hand, 8-hydroxy-2-deoxyguanosine (8-OHdG), nitric oxide (NO), interleukin-6 (IL-6), nuclear factor kappa beta (NF-kβ), malondialdehyde (MDA), and tumor necrosis factor-alpha (TNF-α) levels in the CP + CUR-PP groups were lower than those in the CP group (p < 0.05). However, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and reduced glutathione (GSH) parameters were higher in the CP + CUR-PP groups compared to the CP group (p < 0.05). It is thought that the similarity of Groups 5 and 6 with Group 4 in Aβ1-42, pTAU, GLU, and GABA parameters hinder the determination of treatment protection however, they might have a therapeutic effect if the applied dose or study duration were changed. This study attempted to evaluate the effects of a CUR-PP combination on CP-induced brain damage in rats by measuring biochemical parameters and performing histopathological examinations. Based on the findings, this CUR-PP combination could be considered an alternative medicine option in cases with conditions similar to those evaluated in this study.
Topics: Animals; Polyunsaturated Alkamides; Benzodioxoles; Curcumin; Piperidines; Alkaloids; Rats; Cyclophosphamide; Male; Brain Injuries; Rats, Wistar; Brain; Oxidative Stress; Neuroprotective Agents
PubMed: 38953502
DOI: 10.1002/jbt.23760 -
Organic Letters Jul 2024A palladium-catalyzed cascade carbonylation reaction of 2-bromo--(2-iodophenyl)benzamides with benzylidenecyclopropanes for the synthesis of fused isoindolinone...
A palladium-catalyzed cascade carbonylation reaction of 2-bromo--(2-iodophenyl)benzamides with benzylidenecyclopropanes for the synthesis of fused isoindolinone derivatives has been developed. A broad range of 6/5/6/6 tetracyclic isoindolinone products were efficiently prepared in moderate to good yields with diverse substitution. Two carbonyl groups were incorporated into the substrates in a single step with the formation of four carbon-carbon bonds and two carbon-heteroatom bonds.
PubMed: 38953484
DOI: 10.1021/acs.orglett.4c01451 -
The Chinese Journal of Dental Research Jun 2024To evaluate the effect of entrapment of curcumin within liposomal formulation and the sustained release attitude of the formulated liposomal gel on periodontal defects... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate the effect of entrapment of curcumin within liposomal formulation and the sustained release attitude of the formulated liposomal gel on periodontal defects in diabetic patients in clinical and biochemical terms.
METHODS
Thirty diabetic patients with periodontitis were randomly assigned to three equal groups and ten healthy participants were assigned as the control group. Group I was subjected to scaling and root planing (SRP) with application of sustained release liposomal curcumin gel. Group II was subjected to scaling and root planning with application of curcumin gel. Group III was subjected to scaling and root planning with application of placebo gel. Group IV (control group), no intervention was done. The following parameters were evaluated before treatment and after 6 and 12 weeks: plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment level (CAL), tumour necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and total antioxidant capacity (TAC).
RESULTS
All study groups showed improvement in clinical and biochemical parameters that are statistically significant. Upon comparing the results of treatment modalities, the highest improvement was achieved in group I followed by group II then group III.
CONCLUSION
Sustained release liposomal curcumin gel enhanced the antioxidant capacity, decreased the inflammatory mediators and showed more improvement in clinical outcome for treatment of periodontitis in diabetic patients.
Topics: Humans; Curcumin; Liposomes; Delayed-Action Preparations; Male; Female; Middle Aged; Adult; Dental Scaling; Periodontitis; Root Planing; Treatment Outcome; Tumor Necrosis Factor-alpha; Antioxidants; Periodontal Index
PubMed: 38953482
DOI: 10.3290/j.cjdr.b5459607 -
The Chinese Journal of Dental Research Jun 2024To evaluate the effect of different adhesives and veneering resins on the shear bond strength (SBS) of polyetheretherketone (PEEK).
OBJECTIVE
To evaluate the effect of different adhesives and veneering resins on the shear bond strength (SBS) of polyetheretherketone (PEEK).
METHODS
A total of 138 PEEK specimens were randomly divided into 6 groups according to adhesive material application: Control (C, no application), Adhese Universal (A) (Ivoclar Vivadent, Schaan, Liechtenstein), Gluma Bond Universal (G) (Heraeus Kulzer, South Bend, IN, USA), G-PremioBOND (P) (GC Corporation, Tokyo, Japan), Single Bond Universal (S) (3M, Saint Paul, MN, USA) and visio.link (V) (Bredent, Senden, Germany). Each adhesive group was divided into two subgroups according to the type of veneering material: Estenia direct composite (D) and Gradia Plus indirect composite (IN) (both GC Corporation). After the veneering process, the specimens were aged by thermal cycling. Kruskal-Wallis and Mann-Whitney U tests were used for SBS analysis (P < 0.05).
RESULTS
The highest SBS results were obtained in the VIN group, followed by the VD, PD, GIN, AIN, AD, SIN, SD, PIN, GD, CIN and CD groups, respectively (P = 0.001). There were no significant differences in terms of the type of veneering composite when the same adhesive was applied (P > 0.05), except for Gluma Bond Universal (P = 0.009). All the adhesives tested showed clinically acceptable SBS results.
CONCLUSION
Visio.link offered the highest adhesion to PEEK, whereas the tested universal adhesives may be used as an alternative to visio.link in clinical settings. It was determined that changing the veneer type has no statistical difference when the same adhesive material is used.
Topics: Benzophenones; Polyethylene Glycols; Ketones; Composite Resins; Polymers; Dental Veneers; Shear Strength; Materials Testing; Dental Bonding; Humans; Resin Cements; Dental Stress Analysis; Bisphenol A-Glycidyl Methacrylate
PubMed: 38953481
DOI: 10.3290/j.cjdr.b5459601 -
Angewandte Chemie (International Ed. in... Jul 2024While supported metal nanoparticles (NPs) have shown significant promise in heterogeneous catalysis, precise control over their interaction with the support, which...
While supported metal nanoparticles (NPs) have shown significant promise in heterogeneous catalysis, precise control over their interaction with the support, which profoundly impacts their catalytic performance, remains a significant challenge. In this study, Pt NPs are incorporated into thioether-functionalized covalent organic frameworks (denoted COF-Sx), enabling precise control over the size and electronic state of Pt NPs by adjusting the thioether density dangling on the COF pore walls. Notably, the resulting Pt@COF-Sx demonstrate exceptional selectivity (>99%) in catalytic hydrogenation of p-chloronitrobenzene to p-chloroaniline, in sharp contrast to the poor selectivity of Pt NPs embedded in thioether-free COFs. Furthermore, the conversion over Pt@COF-Sx exhibits a volcano-type curve as the thioether density increases, due to the corresponding change of accessible Pt sites. This work provides an effective approach to regulating the catalysis of metal NPs via their microenvironment modulation, with the aid of rational design and precise tailoring of support structure.
PubMed: 38953455
DOI: 10.1002/anie.202410097 -
Small (Weinheim An Der Bergstrasse,... Jul 2024Polyimide aerogels have been extensively used in thermal protection domain because they possess a combination of intrinsic characteristics of aerogels and unique...
Polyimide aerogels have been extensively used in thermal protection domain because they possess a combination of intrinsic characteristics of aerogels and unique features of polyimide. However, polyimide aerogels still suffer significant thermally induced shrinkage at temperatures above 200 °C, restricting their application at high temperature. Here, a novel "double-phase-networking" strategy is proposed for fabricating a lightweight and mechanically robust polyimide hybrid aerogel by forming silica-zirconia-phase networking skeletons, which possess exceptional dimensional stability in high-temperature environments and superior thermal insulation. The rational mechanism responsible for the formation of double-phase-networking aerogel is further explained, generally attributing to chemical crosslinking reactions and supramolecular hydrogen bond interactions derived from the main chains of polyimide and silane/zirconia precursor/sol. The as-prepared aerogels exhibit excellent high-temperature (270 °C) dimensional stability (5.09% ± 0.16%), anti-thermal-shock properties, and low thermal conductivity. Moreover, the hydrophobic treatment provides aerogels high water resistance with water contact angle of 136.9°, further suggestive of low moisture content of 3.6% after exposure to 70 °C and 85% relative humidity for 64 h. The proposed solution for significantly enhancing high-temperature dimensional stability and thermal insulation provides a great supporting foundation for fabricating high-performance organic aerogels as thermal protection materials in aerospace.
PubMed: 38953403
DOI: 10.1002/smll.202404104 -
ChemSusChem Jul 2024In the chemical industry, formaldehyde is an important bulk chemical. The traditional synthesis of formaldehyde involves an energy intensive oxidation of methanol over a...
In the chemical industry, formaldehyde is an important bulk chemical. The traditional synthesis of formaldehyde involves an energy intensive oxidation of methanol over a metal oxide catalyst. The selective electrochemical oxidation of methanol is challenging. Herein, we report a catalytic system with an immobilized TEMPO electrode that selectively oxidizes methanol to formaldehyde with high turnover numbers. Upon the addition of various organic and inorganic bases, the activity of the catalyst could be tuned. The highest Faradaic efficiency that was achieved was 97.5 %, the highest turnover number was 17100. Additionally, we found that the rate determining step changed from the step in which the carbonyl specie is created from the methanol-TEMPO adduct to the oxidative regeneration of the TEMPO species. Finally, we showed that the system could be applied to the oxidation of other aliphatic alcohols.
PubMed: 38953395
DOI: 10.1002/cssc.202400582 -
Cancer Medicine Jul 2024Lenvatinib (LEN) and atezolizumab + bevacizumab (A + B) have drastically changed the treatment paradigm for advanced hepatocellular carcinoma (HCC). Before these... (Comparative Study)
Comparative Study
BACKGROUND
Lenvatinib (LEN) and atezolizumab + bevacizumab (A + B) have drastically changed the treatment paradigm for advanced hepatocellular carcinoma (HCC). Before these landmark trials, sorafenib (SOR) served as the standard first-line treatment for a decade. Our study aimed to assess the outcomes of HCC patients treated during the SOR era (2008-2018) in contrast to those in the post-SOR era (2018-2021), of which the predominant first-line treatments were LEN or A + B.
METHODS
Inclusion criteria of the study were all HCC patients in the Canadian province of Alberta who started first-line systemic therapy at cancer centers between 1 January 2008 and 31 December 2021. Survival outcomes, including overall survival (OS) and progression-free survival (PFS), along with clinician-assessed response rate (RR), were subject to retrospective analysis.
RESULTS
Of 372 total patients, 230 received treatment in the SOR era and 142 in the post-SOR era. The demographic and clinical characteristics for the SOR era and post-SOR era groups are as follows, respectively: the median age was 63 and 64 years, 80% and 81% were male, and 24% and 11% were of East Asian ethnicity. Before receiving systemic treatment, 40% and 33% received TACE, 7% and 9% received TARE, and 3% and 14% received SBRT in the two eras, respectively. In the post-SOR era, patients received A + B (23%), LEN (51%), and SOR (23%) as first-line treatment. There was a statistically significant improvement in RR (15% vs. 26%; p = 0.02), median PFS (3.8 months vs. 7.9 months; p < 0.0001), and median OS (9.8 months vs. 17.0 months; p < 0.0001).
CONCLUSIONS
In this retrospective multicenter real-world study, HCC patients treated in the post-SOR era, where LEN and A + B were commonly used first-line treatments, exhibited superior OS, PFS, and RR compared to patients treated in the SOR era. The findings of this study affirm the tangible progress achieved in the real world in enhancing outcomes for HCC patients through advancements in treatments over the past 15 years.
Topics: Humans; Carcinoma, Hepatocellular; Liver Neoplasms; Quinolines; Phenylurea Compounds; Male; Female; Middle Aged; Sorafenib; Retrospective Studies; Aged; Antibodies, Monoclonal, Humanized; Antineoplastic Combined Chemotherapy Protocols; Progression-Free Survival; Bevacizumab; Treatment Outcome; Immunotherapy
PubMed: 38953381
DOI: 10.1002/cam4.7415