2069-56-9Relevant academic research and scientific papers
Decarboxylative Hydroxylation of Benzoic Acids
Ritter, Tobias,Su, Wanqi,Xu, Peng
supporting information, p. 24012 - 24017 (2021/10/06)
Herein, we report the first decarboxylative hydroxylation to synthesize phenols from benzoic acids at 35 °C via photoinduced ligand-to-metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation. The aromatic decarboxylative hydroxylation is synthetically promising due to its mild conditions, broad substrate scope, and late-stage applications.
Radical Decarboxylative Carbometalation of Benzoic Acids: A Solution to Aromatic Decarboxylative Fluorination
Xu, Peng,López-Rojas, Priscila,Ritter, Tobias
supporting information, p. 5349 - 5354 (2021/05/05)
Abundant aromatic carboxylic acids exist in great structural diversity from nature and synthesis. To date, the synthetically valuable decarboxylative functionalization of benzoic acids is realized mainly by transition-metal-catalyzed decarboxylative cross couplings. However, the high activation barrier for thermal decarboxylative carbometalation that often requires 140 °C reaction temperature limits both the substrate scope as well as the scope of suitable reactions that can sustain such conditions. Numerous reactions, for example, decarboxylative fluorination that is well developed for aliphatic carboxylic acids, are out of reach for the aromatic counterparts with current reaction chemistry. Here, we report a conceptually different approach through a low-barrier photoinduced ligand to metal charge transfer (LMCT)-enabled radical decarboxylative carbometalation strategy, which generates a putative high-valent arylcopper(III) complex, from which versatile facile reductive eliminations can occur. We demonstrate the suitability of our new approach to address previously unrealized general decarboxylative fluorination of benzoic acids.
Development of Positron Emission Tomography (PET) Radiotracers for the GABA Transporter 1 (GAT-1)
Sowa, Alexandra R,Brooks, Allen F,Shao, Xia,Henderson, Bradford D,Sherman, Phillip S.,Arteaga, Janna,Stauff, Jenelle,Lee, Adam C.,Koeppe, Robert A.,Scott, Peter J. H.,Kilbourn, Michael R.
, (2018/05/29)
In vivo PET imaging of the γ-aminobutyric acid (GABA) receptor complex has been accomplished using radiolabeled benzodiazepine derivatives, but development of specific presynaptic radioligands targeting the neuronal membrane GABA transporter type 1 (GAT-1) has been less successful. The availability of new structure-activity studies of GAT-1 inhibitors and the introduction of a GAT-1 inhibitor (tiagabine, Gabatril) into clinical use prompted us to reinvestigate the syntheses of PET ligands for this transporter. Initial synthesis and rodent PET studies of N-[11C]methylnipecotic acid confirmed the low brain uptake of that small and polar molecule. The common design approach to improve blood-brain barrier permeability of GAT-1 inhibitors is the attachment of a large lipophilic substituent. We selected an unsymmetrical bis-aromatic residue attached to the ring nitrogen by a vinyl ether spacer from a series recently reported by Wanner and coworkers. Nucleophilic aromatic substitution of an aryl chloride precursor with [18F]fluoride was used to prepare the desired candidate radiotracer (R,E/Z)-1-(2-((4-fluoro-2-(4-[18F]fluorobenzoyl)styryl)oxy)ethyl)piperidine-3-carboxylic acid ((R,E/Z)-[18F]10). PET studies in rat showed no brain uptake, which was not altered by pretreatment of animals with the P-glycoprotein inhibitor cyclosporine A, indicating efflux by Pgp was not responsible. Subsequent PET imaging studies of (R,E/Z)-[18F]10 in rhesus monkey brain showed very low brain uptake. Finally, to test if the free carboxylic acid group was the likely cause of poor brain uptake, PET studies were done using the ethyl ester derivative of (R,E/Z)-[18F]10. Rapid and significant monkey brain uptake of the ester was observed, followed by a slow washout over 90 minutes. The blood-brain barrier permeability of the ester supports a hypothesis that the free acid function limits brain uptake of nipecotic acid-based GAT-1 radioligands, and future radiotracer efforts should investigate the use of carboxylic acid bioisosteres.
Evaluation of the role of isostructurality in fluorinated phenyl benzoates
Dey, Dhananjay,Chopra, Deepak
, p. 5117 - 5128 (2018/03/01)
In this report, the occurrence of three-, two-, and one-dimensional (3D, 2D, and 1D) isostructurality in phenyl benzoate (D00) and their fluorinated analogues was investigated in terms of their molecular assembly in solid state structures. A onedimensional C-H?O=C chain is observed as a robust motif (～ -21 kJ/mol) in the formation of the supramolecular architectures in these isostructural compounds. The isomorphous crystal structures exhibit 3D isostructurality or vice versa. The crystal packing shows that weak intermolecular C-H ? F, C-H ? O, C- H ? π interactions, and π ? π stacking are the main contributors providing stability toward the crystal lattice. The nature and energetics of all the geometrically or energetically equivalent building blocks associated with similar or different intermolecular interactions delineate the role of different molecular pairs in the crystal structures. The fingerprint plots of the isostructural set of crystal structures help to understand the similarities and the differences in the various interatomic contacts. A comparison of these crystal structures with fluorinated N-phenyl benzamides shows the change in supramolecular assembly in terms of intermolecular interactions as well as the lattice energy due to the participation of a strong donor (N-H).
Aryl formate as bifunctional reagent: Applications in palladium-catalyzed carbonylative coupling reactions using in situ generated CO
Li, Haoquan,Neumann, Helfried,Beller, Matthias,Wu, Xiao-Feng
supporting information, p. 3183 - 3186 (2014/04/03)
After decades of development, carbonylation reactions have become one of the most powerful tools in modern organic synthesis. However, the requirement of CO gas limits the applications of such reactions. Reported herein is a versatile and practical protocol for carbonylative reactions which rely on the cooperation of phenyl formate and nonaflate, and the generation of CO in situ. This protocol has a high functional-group tolerance and could be applied in carbonylations with C, N, and, O nucleophiles. The corresponding amides, alkynones, furanones, and aryl benzoates were synthesized in good yields. Transformers: A versatile and practical protocol for carbonylation reactions involve the cooperation of phenyl formate and nonaflate with generation of CO in situ. This protocol has a high functional-group tolerance and could be applied in carbonylative couplings with C, N, and O nucleophiles. The corresponding amides, alkynones, furanones, and aryl benzoates were synthesized in good yield.
Synthesis and evaluation of N-substituted nipecotic acid derivatives with an unsymmetrical bis-aromatic residue attached to a vinyl ether spacer as potential GABA uptake inhibitors
Quandt, Gabriele,H?fner, Georg,Wanner, Klaus T.
supporting information, p. 3363 - 3378 (2013/07/28)
γ-Amino butyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system (CNS). A malfunction of the GABAergic neurotransmission is connected to several neuronal disorders like epilepsy, Alzheimer's disease, neuropathic
Significant promoting effects of Lewis acidity on Au-Pd systems in the selective oxidation of aromatic hydrocarbons
Liu, Hongli,Li, Yingwei,Jiang, Huanfeng,Vargas, Carolina,Luque, Rafael
supporting information, p. 8431 - 8433 (2012/10/29)
An unprecedented synergistic effect, obtained for rationally designed Au-Pd alloy nanoparticles supported on an acidic metal-organic framework (MOF), in the aerobic oxidation of the primary C-H bonds in toluene and derivates is reported.
A general and efficient palladium-catalyzed alkoxycarbonylation of phenols to form esters through in situ formed aryl nonaflates
Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
supporting information; experimental part, p. 3831 - 3834 (2012/05/20)
Esters made easy! A general and efficient methodology for the palladium-catalyzed alkoxycarbonylation of in situ formed aryl nonaflates has been developed (see scheme). Both homo- and cross-esterifications are possible. DPPF=1,1′-bis(diphenylphosphino)ferrocene. Copyright
Baeyer-Villiger oxidation of ketones to esters with sodium percarbonate/trifluoroacetic acid
Olah,Wang,Trivedi,Surya Prakash
, p. 739 - 740 (2007/10/02)
Sodium percarbonate in trifluoroacetic acid has been found to be an effective reagent for the Baeyer-Villiger oxidation of ketones to esters. The scope and limitations of the reaction were explored.
