60718-45-8Relevant academic research and scientific papers
Combined Photoredox and Carbene Catalysis for the Synthesis of γ-Aryloxy Ketones
Wang, Pengzhi,Fitzpatrick, Keegan P.,Scheidt, Karl A.
supporting information, p. 518 - 524 (2021/12/16)
N-heterocyclic carbenes (NHCs) have emerged as catalysts for the construction of C?C bonds in the synthesis of substituted ketones under single-electron processes. Despite these recent reports, there still remains a need to increase the utility and practicality of these reactions by exploring new radical coupling partners. Herein, we report the synthesis of γ-aryloxyketones via combined NHC/photoredox catalysis. In this reaction, an α-aryloxymethyl radical is generated via oxidation of an aryloxymethyl potassium trifluoroborate salt, which is then added into styrene derivatives to provide a stabilized benzylic radical. Subsequent radical-radical coupling reaction with an azolium radical affords the γ-aryloxy ketone products. (Figure presented.).
Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids
Betori, Rick C.,Davies, Anna V.,Fitzpatrick, Keegan P.,Scheidt, Karl A.
supporting information, p. 9143 - 9148 (2020/03/30)
As a key element in the construction of complex organic scaffolds, the formation of C?C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single-electron chemistry have enabled new methods for the formation of various C?C bonds. Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N-heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late-stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies.
Efficient Copper-Catalyzed Multicomponent Synthesis of N-Acyl Amidines via Acyl Nitrenes
Van Vliet, Kaj M.,Polak, Lara H.,Siegler, Maxime A.,Van Der Vlugt, Jarl Ivar,Guerra, Célia Fonseca,De Bruin, Bas
supporting information, p. 15240 - 15249 (2019/10/19)
Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper-catalyzed three-component reaction of aryl acetylenes, amines, and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO2 as the only byproduct. Transformation of the dioxazolones on the Cu catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For nonaromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 min. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple copper(I) iodide (CuI) as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol %. The herein reported procedure not only provides a new, practical, and direct route to N-acyl amidines but also represents a new type of C-N bond formation.
N-methylimidazole-catalyzed synthesis of carbamates from hydroxamic acids via the lossen rearrangement
Yoganathan, Sabesan,Miller, Scott J.
supporting information, p. 602 - 605 (2013/04/11)
An efficient, one-pot, N-methylimidazole (NMI) accelerated synthesis of aromatic and aliphatic carbamates via the Lossen rearrangement is reported. NMI is a catalyst for the conversion of isocyanate intermediates to the carbamates. Moreover, the utility of arylsulfonyl chloride in combination with NMI minimizes the formation of often-observed hydroxamate-isocyanate dimers during the sequence. Under the present conditions, lowering of temperatures is also possible, enabling a mild protocol.
[Pd(μ-Br)(PtBu3)]2 as a highly active isomerization catalyst: Synthesis of enol esters from allylic esters
Mamone, Patrizia,Gruenberg, Matthias F.,Fromm, Andreas,Khan, Bilal A.,Goossen, Lukas J.
supporting information; experimental part, p. 3716 - 3719 (2012/09/08)
The dimeric Pd(I)-complex [Pd(μ-Br)(PtBu3)] 2 was found to be highly active for catalyzing double-bond migration in various substrates such as unsaturated ethers, alcohols, amides, and arenes, under mild conditions. It efficiently mediates the conversion of allylic esters into enol esters, rather than inserting into the allylic C-O bond. The broad applicability of this reaction was demonstrated with the synthesis of 22 functionalized enol esters.
Mild decarboxylative activation of malonic acid derivatives by 1,1′-carbonyldiimidazole
Lafrance, Danny,Bowles, Paul,Leeman, Kyle,Rafka, Robert
supporting information; experimental part, p. 2322 - 2325 (2011/06/26)
Chemical equations presented. Malonic acid derivatives undergo unusually mild decarboxylation when treated with N,N′-carbonyldiimidazole (CDI) at room temperature to generate the carbonyl imidazole moiety in high yield, which can be reacted further with a variety of nucleophiles in an efficient one-pot process.
Synthesis of spirotetramates via a Diels-Alder approach
Butt, Nicholas A.,Moody, Christopher J.
supporting information; experimental part, p. 2224 - 2227 (2011/06/22)
Chemical equations presented. A study toward the unusual spirotetramate core of the pyrroindomycin antibiotics employing an intermolecular Diels-Alder reaction of an exo-methylene tetramic acid dienophile is described. The exo-methylene tetramate is readi
Expedient synthesis of 3-hydroxyisoquinolines and 2-hydroxy-1,4- naphthoquinones via one-pot aryne acyl-alkylation/condensation
Allan, Kevin M.,Hong, Boram D.,Stoltz, Brian M.
supporting information; experimental part, p. 4960 - 4964 (2010/02/15)
A convenient method is disclosed for the synthesis of both 3-hydroxyisoquinolines and 2-hydroxy-1,4-naphthoquinones from β-ketoesters using a one-pot aryne acyl-alkylation/condensation procedure. When performed in conjunction with a one-step method for the synthesis of the β-ketoester substrates, this method provides a new route to these polyaromatic structures in only two steps from commercially available carboxylic acid starting materials. The utility of this approach is demonstrated in the synthesis of the atropisomeric P,N-ligand, QUINAP. The Royal Society of Chemistry 2009.
Acylguanidines as bioisosteres of guanidines: NG-acylated imidazolylpropylguanidines, a new class of histamine h2 receptor agonists
Ghorai, Prasanta,Kraus, Anja,Keller, Max,G?tte, Carsten,Igel, Patrick,Schneider, Erich,Schnell, David,Bernhardt, Günther,Dove, Stefan,Zabel, Manfred,Elz, Sigurd,Seifert, Roland,Buschauer, Armin
supporting information; experimental part, p. 7193 - 7204 (2009/10/02)
N1-Aryl(heteroaryl)alkyl-N2-[3-(1H-imidazol-4-yl) propyl]guanidines are potent histamine H2-receptor (H2R) agonists, but their applicability is compromised by the lack of oral bioavailability and CNS penetration. To improve pharmacokinetics, we introduced carbonyl instead of methylene adjacent to the guanidine moiety, decreasing the basicity of the novel H2R agonists by 4-5 orders of magnitude. Some acylguanidines with one phenyl ring were even more potent than their diaryl analogues. As demonstrated by HPLC-MS, the acylguanidines (bioisosteres of the alkylguanidines) were absorbed from the gut of mice and detected in brain. In GTPase assays using recombinant receptors, acylguanidines were more potent at the guinea pig than at the human H2R. At the hH1R and hH3R, the compounds were weak to moderate antagonists or partial agonists. Moreover, potent partial hH4R agonists were identified. Receptor subtype selectivity depends on the imidazolylpropylguanidine moiety (privileged structure), opening an avenue to distinct pharmacological tools including potent H4R agonists.
Synthesis and antibacterial activity of novel and potent DNA gyrase inhibitors with azole ring
Tanitame, Akihiko,Oyamada, Yoshihiro,Ofuji, Keiko,Fujimoto, Mika,Suzuki, Kenji,Ueda, Tomohiko,Terauchi, Hideo,Kawasaki, Motoji,Nagai, Kazuo,Wachi, Masaaki,Yamagishi, Jun-Ichi
, p. 5515 - 5524 (2007/10/03)
The pyrazole, oxazole and imidazole derivatives synthesized in this study exhibited potent antibacterial activity against multidrug resistant Gram-positive bacteria with minimal inhibitory concentration values equivalent to those against susceptible strains. The 4-piperidyl moiety and the pyrazole ring in 1-(3-chlorophenyl)-5-(4-phenoxyphenyl)-3-(4-piperidyl)pyrazole 2, which has previously shown improved DNA gyrase inhibition and target-related antibacterial activity, were transformed to other groups and the in vitro antibacterial activity of the synthesized compounds was evaluated. The selected pyrazole, oxazole and imidazole derivatives showed moderate inhibition against DNA gyrase and topoisomerase IV with similar IC50 values (IC 50 = 9.4-25 μg/mL). In addition, many of the pyrazole, oxazole a1nd imidazole derivatives synthesized in this study exhibited potent antibacterial activity against quinolone-resistant clinical isolates and coumarin-resistant laboratory isolates of Gram-positive bacteria with minimal inhibitory concentration values equivalent to those against susceptible strains.
