Development of Fluorine-18 Labeled Metabolically Activated Tracers for Imaging of Drug Efflux Transporters with Positron Emission Tomography
摘要:
Increased activity of efflux transporters, e.g., P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), at the blood brain barrier is a pathological hallmark of many neurological diseases, and the resulting multiple drug resistance represents a major clinical challenge. Noninvasive imaging of transporter activity can help to clarify the underlying mechanisms of drug resistance and facilitate diagnosis, patient stratification, and treatment monitoring. We have developed a metabolically activated radiotracer for functional imaging of P-gp/BCRP activity with positron emission tomography (PET). In preclinical studies, the tracer showed excellent initial brain uptake and clean conversion to the desired metabolite, although at a sluggish rate. Blocking with P-gp/BCRP modulators led to increased levels of brain radioactivity; however, dynamic PET did not show differential clearance rates between treatment and control groups. Our results provide proof-of-concept for development of prodrug tracers for imaging of P- /BCRP function in vivo but also highlight some challenges associated with this strategy.
Electrochemically Promoted Nickel-Catalyzed Carbon–Sulfur Bond Formation
作者:Yang Wang、Lingling Deng、Xiaochen Wang、Zhengguang Wu、Yi Wang、Yi Pan
DOI:10.1021/acscatal.8b04633
日期:2019.3.1
This work describes a nickel-catalyzed Ullmann-type thiolation of aryl iodidesunder mild electrochemical conditions. The simple undivided cell with graphene/nickel foam electrode setups offers excellent substrate tolerance, affording aryl and alkyl sulfides in good chemical yields. Furthermore, the mechanism for this electrochemical cross-coupling reaction has been investigated by cyclic voltammetry
Electrochemical Thiolation and Borylation of Arylazo Sulfones with Thiols and B
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pin
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作者:Rongkang Wang、Fangming Chen、Lvqi Jiang、Wenbin Yi
DOI:10.1002/adsc.202001518
日期:2021.3.29
arylazo sulfones were used as radical precursors for carbon‐heteroatom bond formation under electrochemical conditions. Moreover, the scalability of this approach was evaluated by performing the electrochemical thiolation and borylation of arylazo sulfones with thiols and B2pin2 on a gram scale. This protocol not only avoided the use of stoichiometric oxidants, metal catalysts, activating agents and
Metal-Free Cercosporin-Photocatalyzed C-S Coupling for the Selective Synthesis of Aryl Sulfides under Mild Conditions
作者:Jia Li、Wenhao Bao、Yan Zhang、Yijian Rao
DOI:10.1002/ejoc.201901444
日期:2019.11.14
cercosporin at aspects of photophysics and photobiology, its application in photocatalysis has been rarely reported. Herein we report cercosporin‐photocatalyzed selective synthesis of aryl sulfides undermild and green conditions. The gram‐scale reaction can proceed using cercosporin‐containing fermentation supernatant without purification.
Iodine(III) Enabled Dehydrogenative Aryl C−S Coupling by in situ Generated Sulfenium Ion
作者:Khokan Choudhuri、Saikat Maiti、Prasenjit Mal
DOI:10.1002/adsc.201801510
日期:2019.3.5
Due to the normal polarity preferences, arenes form stable complexes with thiols through S−H⋅⋅⋅π interaction and direct dehydrogenative aryl C−S coupling is usually restricted. We report here an umpolung based one pot and direct C−S coupling approach under metal free and mild condition. Electrophile sulfenium ions were generated in situ from thiols using iodine(III) reagent PhI(OAc)2 (PIDA) and subsequently
An application for dechalcogenization of aryl dichalcogenides via copper catalysis to synthesize aryl chalcogenides is disclosed. This approach is highlighted by the practical conditions, broad substrate scope, and good functional group tolerance with several sensitive groups such as aldehyde, ketone, ester, amide, cyanide, alkene, nitro, and methylsulfonyl. Furthermore, the robustness of this methodology