The dynamic Lewis multicore system (DLMCS) which integrates the Lewis acidic boron center(s) and an ammonium salt in one molecule has shown good catalytic performance in polymer synthesis. Inspired by the insightful intramolecular ammonium cation assisted mechanism, herein, we communicated a superior organoboron system by replacing a nitrogen atom with a phosphorus atom. The upgraded mono-, di-, and trinuclear organoboron catalysts show significantly improved catalytic performance and heat resistance for versatile epoxideinvolved transformations, including ring-opening copolymerization of epoxides and cyclic anhydrides, copolymerization of CO 2 and epoxides, and ring-opening polymerization of epoxides. 11 B NMR, single-crystal X-ray diffraction, and DFT results imply that the replacing nitrogen with phosphorus in an onium cation led to an effective epoxide activation and nucleophilic attack of the counterion on the activated epoxide, which remarkably shortened the initiation period and accelerated chain expansion, resulting in the obvious improvement of the activity. The upgraded phosphonium-containing organoboron system combined with the mechanism study and insightful understanding would be instructive in designing advanced metal-free catalysts.
Introduction: Remimazolam is an ultra-short-acting benzodiazepine sedative agent commonly used in general anesthesia, procedural sedation, and intensive care unit (ICU) sedation. This study aimed to explore the efficacy and safety of remimazolam versus propofol for the induction and maintenance of general anesthesia in preschool-age children undergoing elective surgery.Methods and analysis: In this multicenter, randomized, single-blind, positive-controlled non-inferior clinical trial, one hundred ninety-two children aged 3–6 years will be randomly allocated as a 3:1 ratio into two groups: Group R with an intravenous dose of remimazolam 0.3 mg/kg for the induction of anesthesia followed by a constant infusion rate of remimazolam 1–3 mg/kg/h to maintain anesthesia, and Group P with an intravenous dose of propofol 2.5 mg/kg for the induction of anesthesia followed by a constant infusion rate of propofol 4–12 mg/kg/h to maintain anesthesia. The primary outcome will be the rate of the successful induction and maintenance of anesthesia. The secondary outcomes will include the time to LoC, the Bispectral Index (BIS) value, awakening time, extubation time, post-anesthesia care unit (PACU) discharge time, usage of additional sedative drugs during the induction period, usage of remedial drugs in PACU, emergence delirium, pain in PACU, behavior scores at day 3 after surgery, parental and anesthesiologists’ satisfaction, and adverse events.Ethics and dissemination: This study has been approved by the ethics review boards at all participating hospitals. The Ethics Committee of the Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University (Reference No. LCKY 2020-380, November 13, 2020) is the central ethics committee.
The ability to access structurally diverse and complex compounds efficiently and economically from readily available starting materials is an important goal in organic synthesis and medicinal chemistry. Herein, DABCO-catalyzed reactions...
Comprehensive SummarySynthesis of diverse polythioimidocarbonates via ring‐opening copolymerization of epoxides and isothiocyanates catalyzed by organoboron catalyst was reported herein. Both aromatic and aliphatic isothiocyanates underwent successful copolymerization with terminal and internal epoxides, allowing for the precise tuning of the performance of the resultant copolymers over a broad range. The wide scope of available isothiocyanates and epoxides enables the direct construction of sulfur‐containing functional polymers featuring both high glass transition temperature and refractive index. Additionally, it was observed that aromatic isothiocyanates polymerize much faster than aliphatic ones, and the reactivity difference facilitated the one‐step synthesis of block polymers from mixed aromatic isothiocyanates, aliphatic isothiocyanates and epoxides due to the preferential incorporation of aromatic isothiocyanates than the aliphatic analogues during their alternating copolymerization with epoxides. The produced polythioimidocarbonates can be used as positive resists for electron beam lithography (sensitivity of 130 μC/cm2 and contrast of 1.53 for poly(CHO‐alt‐EITC)). Coupling with their high refractive index (1.58‐1.68), polythioimidocarbonates might find functional applications in optics. These results render ring‐opening copolymerization of epoxides and isothiocyanates a facile route to enrich functional polymer library.This article is protected by copyright. All rights reserved.
We reported a cupreidine catalyzed enantioselective cascade cyclization reaction of 2alkynyl-3,3-difluoro-3H-indole and 2-mercaptoimidazole under simple and mild conditions. The corresponding chiral gem-difluorinated C2-spiro indolines were obtained in moderate to good yields and enantioselectivities, which could be interesting compounds from synthetic and medicinal chemistry points of view. This work represents the first catalytic enantioselective example of utilizing 2alkynyl-3,3-difluoro-3H-indoles as the bis-electrophiles in a cyclization reaction.
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