| 1. |
- Erbing, Elis, et al.
(författare)
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General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols : The Importance of the Halide Ligand
- 2016
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 22:44, s. 15659-15663
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Tidskriftsartikel (refereegranskat)abstract
- Remarkably simple Ir-III catalysts enable the isomerization of primary and sec-allylic alcohols under very mild reaction conditions. X-ray absorption spectroscopy (XAS) and mass spectrometry (MS) studies indicate that the catalysts, with the general formula [Cp*Ir-III], require a halide ligand for catalytic activity, but no additives or additional ligands are needed.
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| 2. |
- Bermejo Gomez, Antonio, et al.
(författare)
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Iridium-Catalyzed Isomerization/Bromination of Allylic Alcohols : Synthesis of alpha-Bromocarbonyl Compounds
- 2014
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 20:34, s. 10703-10709
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Tidskriftsartikel (refereegranskat)abstract
- alpha-Brominated ketones and aldehydes, with two adjacent electrophilic carbon atoms, are highly valuable synthetic intermediates in organic synthesis, however, their synthesis from unsymmetrical ketones is very challenging, and current methods suffer from low selectivity. We present a new, reliable, and efficient method for the synthesis of alpha-bromocarbonyl compounds in excellent yields and with excellent selectivities. Starting from allylic alcohols as the carbonyl precursors, the combination of a 1,3-hydrogen shift catalyzed by iridium(III) with an electrophilic bromination gives alpha-bromoketones and aldehydes in good to excellent yields. The selectivity of the process is determined by the structure of the starting allylic alcohol; thus, alpha-bromoketones formally derived from unsymmetrical ketones can be synthesized in a straightforward and selective manner.
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| 3. |
- Cairns, Andrew G., et al.
(författare)
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Increased Brain Exposure of an Alpha-Synuclein Fibrillization Modulator by Utilization of an Activated Ester Prodrug Strategy
- 2018
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Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 9:11, s. 2542-2547
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Tidskriftsartikel (refereegranskat)abstract
- Previous work in our laboratories has identified a series of peptidomimetic 2-pyridone molecules as modulators of alpha-synuclein (α-syn) fibrillization in vitro. As a first step toward developing molecules from this scaffold as positron emission tomography imaging agents, we were interested in evaluating their blood-brain barrier permeability in nonhuman primates (NHP) in vivo. For this purpose, 2-pyridone 12 was prepared and found to accelerate α-syn fibrillization in vitro. Acid 12, and its acetoxymethyl ester analogue 14, were then radiolabeled with 11C (t1/2 = 20.4 min) at high radiochemical purity (>99%) and high specific radioactivity (>37 GBq/μmol). Following intravenous injection of each compound in NHP, a 4-fold higher radioactivity in brain was observed for [11C]14 compared to [11C]12 (0.8 vs 0.2 SUV, respectively). [11C]14 was rapidly eliminated from plasma, with [11C]12 as the major metabolic product observed by radio-HPLC. The presented prodrug approach paves the way for future development of 2-pyridones as imaging biomarkers for in vivo imaging of α-synuclein deposits in brain.
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| 4. |
- Erbing, Elis, et al.
(författare)
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Base- and Additive-Free Ir-Catalyzed ortho-Iodination of Benzoic Acids : Scope and Mechanistic Investigations
- 2018
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 8:2, s. 920-925
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Tidskriftsartikel (refereegranskat)abstract
- A protocol for the C-H activation/iodination of benzoic acids catalyzed by a simple iridium complex has been developed. The method described in this paper allows the ortho-selective iodination of a variety of benzoic acids under extraordinarily mild conditions in the absence of any additive or base in 1,1,1,3,3,3-hexafluoroisopropanol as the solvent. The iridium catalyst used tolerates air and moisture, and selectively gives ortho-iodobenzoic acids with high conversions. Mechanistic investigations revealed that an Ir(III)/Ir(V) catalytic cycle operates, and that the unique properties of HFIP enables the C-H iodination using the carboxylic moiety as a directing group.
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| 5. |
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| 6. |
- Krasikova, Raisa, et al.
(författare)
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Synthesis and Preclinical Evaluation of 6-[18F]Fluorine-α-methyl-l-tryptophan, a Novel PET Tracer for Measuring Tryptophan Uptake
- 2020
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Ingår i: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 11:12, s. 1756-1761
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Tidskriftsartikel (refereegranskat)abstract
- The positron emission tomography (PET) radioligand α-[11C]methyl-l-tryptophan ([11C]AMT) has been used to assess tryptophan metabolism in cancer, epilepsy, migraine, and autism. Despite its extensive application, the utility of this tracer is currently hampered by the short half-life of the radionuclide used for its labeling (11C, t1/2 = 20.4 min). We herein report the design, synthesis, radiolabeling, and initial in vivo evaluation of a fluorine-18 (18F, t 1/2 = 109.7 min) labeled analogue that is fluorinated in the 6-position of the aromatic ring ([18F]6-F-AMTr). In a head-to-head comparison between [18F]6-F-AMTr and [11C]AMT in mice using PET, peak brain radioactivity, regional brain distribution, and kinetic profiles were similar between the two tracers. [18F]6-F-AMTr was however not a substrate for IDO1 or TPH as determined in in vitro enzymatic assays. The brain uptake of the tracer is thus more likely related to LAT1 transport over the blood-brain barrier than metabolism along the serotonin or kynurenine pathways.
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| 7. |
- Martinez-Erro, Samuel, et al.
(författare)
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2,2-Diiododimedone : a mild electrophilic iodinating agent for the selective synthesis of alpha-iodoketones from allylic alcohols
- 2017
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; 53:71, s. 9842-9845
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Tidskriftsartikel (refereegranskat)abstract
- 2,2-Diiodo-5,5-dimethylcyclohexane-1,3-dione is reported as a new electrophilic iodinating agent that selectively iodinates electron-rich aromatics. In contrast to other common electrophilic iodinating reagents, its mild nature allows it to be used for the selective synthesis of alpha-iodinated carbonyl compounds from allylic alcohols through a 1,3-hydrogen shift/iodination process catalyzed by iridium(III) complexes.
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| 8. |
- Martinez-Erro, Samuel, et al.
(författare)
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Base-Catalyzed Stereospecific Isomerization of Electron-Deficient Allylic Alcohols and Ethers through Ion-Pairing
- 2016
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:40, s. 13408-13414
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Tidskriftsartikel (refereegranskat)abstract
- A mild base-catalyzed strategy for the isomerization of allylic alcohols and allylic ethers has been developed. Experimental and computational investigations indicate that transition metal catalysts are not required when basic additives are present. As in the case of using transition metals under basic conditions, the isomerization catalyzed solely by base also follows a stereospecific pathway. The reaction is initiated by a rate-limiting deprotonation. Formation of an intimate ion pair between an allylic anion and the conjugate acid of the base results in efficient transfer of chirality. Through this mechanism, stereochemical information contained in the allylic alcohols is transferred to the ketone products. The stereospecific isomerization is also applicable for the first time to allylic ethers, yielding synthetically valuable enantioenriched (up to 97% ee) enol ethers.
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| 9. |
- Nguyen, Thanh N, et al.
(författare)
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Global Impact of the COVID-19 Pandemic on Stroke Volumes and Cerebrovascular Events: A 1-Year Follow-up.
- 2023
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Ingår i: Neurology. - 1526-632X. ; 100:4
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Tidskriftsartikel (refereegranskat)abstract
- Declines in stroke admission, IV thrombolysis (IVT), and mechanical thrombectomy volumes were reported during the first wave of the COVID-19 pandemic. There is a paucity of data on the longer-term effect of the pandemic on stroke volumes over the course of a year and through the second wave of the pandemic. We sought to measure the effect of the COVID-19 pandemic on the volumes of stroke admissions, intracranial hemorrhage (ICH), IVT, and mechanical thrombectomy over a 1-year period at the onset of the pandemic (March 1, 2020, to February 28, 2021) compared with the immediately preceding year (March 1, 2019, to February 29, 2020).We conducted a longitudinal retrospective study across 6 continents, 56 countries, and 275 stroke centers. We collected volume data for COVID-19 admissions and 4 stroke metrics: ischemic stroke admissions, ICH admissions, IVT treatments, and mechanical thrombectomy procedures. Diagnoses were identified by their ICD-10 codes or classifications in stroke databases.There were 148,895 stroke admissions in the 1 year immediately before compared with 138,453 admissions during the 1-year pandemic, representing a 7% decline (95% CI [95% CI 7.1-6.9]; p < 0.0001). ICH volumes declined from 29,585 to 28,156 (4.8% [5.1-4.6]; p < 0.0001) and IVT volume from 24,584 to 23,077 (6.1% [6.4-5.8]; p < 0.0001). Larger declines were observed at high-volume compared with low-volume centers (all p < 0.0001). There was no significant change in mechanical thrombectomy volumes (0.7% [0.6-0.9]; p = 0.49). Stroke was diagnosed in 1.3% [1.31-1.38] of 406,792 COVID-19 hospitalizations. SARS-CoV-2 infection was present in 2.9% ([2.82-2.97], 5,656/195,539) of all stroke hospitalizations.There was a global decline and shift to lower-volume centers of stroke admission volumes, ICH volumes, and IVT volumes during the 1st year of the COVID-19 pandemic compared with the prior year. Mechanical thrombectomy volumes were preserved. These results suggest preservation in the stroke care of higher severity of disease through the first pandemic year.This study is registered under NCT04934020.
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| 10. |
- Vazquez-Romero, Ana, et al.
(författare)
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Acid- and Iridium-Catalyzed Tandem 1,3-Transposition/3,1-Hydrogen Shift/Chlorination of Allylic Alcohols
- 2015
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 5:2, s. 708-714
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Tidskriftsartikel (refereegranskat)abstract
- A method for the selective synthesis of alpha-chlorocarbonyls from allylic alcohols is presented. The reaction occurs through an acid- and iridium-catalyzed tandem process that combines a 1,3-transposition, a 3,1-hydrogen shift, and a chlorination process, and can be applied to a wide range of alpha-aromatic and heteroaromatic secondary allylic alcohols. Saturated non-chlorinated ketones or other side-products derived from overchlorination were not detected.
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