69163-82-2Relevant academic research and scientific papers
A Heterogeneous Gold(I)-Catalyzed [2 + 2 + 1] Annulation of Terminal Alkynes, Nitriles, and Oxygen Atoms Leading to 2,5-Disubstituted Oxazoles
Yang, Weisen,Zhang, Rongli,Yi, Feiyan,Cai, Mingzhong
, p. 5204 - 5211 (2017/05/24)
The first heterogeneous gold(I)-catalyzed [2 + 2 + 1] annulation of terminal alkynes, nitriles, and oxygen atoms has been achieved by using an MCM-41-immobilized phosphine-gold(I) complex as catalyst and 8-methylquinoline N-oxide as oxidant under mild conditions, yielding a variety of 2,5-disubstituted oxazoles in good to excellent yields with broad substrate scope. The new heterogeneous gold(I) catalyst can easily be recovered by simple filtration of the reaction solution and recycled for at least eight times without significant loss of activity.
Probing the 'bipolar' nature of the carbonic anhydrase active site: Aromatic sulfonamides containing 1,3-oxazol-5-yl moiety as picomolar inhibitors of cytosolic CA I and CA II isoforms
Krasavin, Mikhail,Korsakov, Mikhail,Dorogov, Mikhail,Tuccinardi, Tiziano,Dedeoglu, Nurcan,Supuran, Claudiu T.
, p. 334 - 347 (2015/07/28)
Abstract A series of potent inhibitors of human carbonic anhydrase (CA) isoforms I and II has been prepared via a direct, chemoselective sulfochlorination of a range of 1,3-oxazolyl benzenes and thiophenes, followed by primary sulfonamide synthesis. The latter functionality is a known zinc-binding group (ZBG) responsible for anchoring the inhibitors to the CA's zinc metal ion. The compound's periphery as well as the overall scaffold geometry was designed to enable optimal interactions with the two distinct sides of the enzyme's active site, one of which is lined with hydrophobic residues and while the other is predominantly hydrophilic. As a result, several compounds inhibiting the therapeutically important cytosolic CA I and CA II in picomolar range have been identified. These compounds are one of the most potent CA inhibitors identified to-date. Not only the remarkable (>10 000-fold), cytosolic CA I and CA II selectivity vs. the membrane-bound CA IX and CA XII isoforms, but also the pronounced CA II/I selectivity observed in some cases, allow considering this series as a set of isoform-selective chemical biology tools and promising starting points for drug candidate development.
Synthesis and Catalytic Use of Gold(I) Complexes Containing a Hemilabile Phosphanylferrocene Nitrile Donor
?koch, Karel,Císa?ová, Ivana,?těpni?ka, Petr
supporting information, p. 15998 - 16004 (2015/11/03)
Removal of the chloride ligand from [AuCl(1-κP)] (2) containing a P-monodentate 1′-(diphenylphosphanyl)-1-cyanoferrocene ligand (1), by using silver(I) salts affords cationic complexes of the type [Au(1)]X, which exist either as cyclic dimers [Au(1)]2X2 (3a, X=SbF6; 3 c, X=NTf2) or linear coordination polymers [Au(1)]nXn (3 a′, X=SbF6; 3 b′, X=ClO4), depending on anion X and the isolation procedure. As demonstrated for 3 a′, the polymers can be readily cleaved by the addition of donors, such as Cl-, tetrahydrothiophene (tht) or 1, giving rise to the parent compound 2, [Au(tht)(1-κP)][SbF6] (5 a) or [Au(1-κP)2][SbF6] (4 a), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au(1-κP)2][SbF6]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf-stable precursors of coordinatively unsaturated AuI fragments, analogous to those that result from the widely used [Au(PR3)(RCN)]X catalysts. The catalytic properties of the Au-1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3-dimethylfuran from (Z)-3-methylpent-2-en-4-yn-1-ol and oxidative cyclisation of alkynes with nitriles to produce 2,5-disubstituted 1,3-oxazoles. Of the compounds tested (2, 3 a′, 3 b′, 3 a, 4 a and 5 a), the best results were consistently achieved with dimer 3 c, which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses.
An efficient [2 + 2 + 1] synthesis of 2,5-disubstituted oxazoles via gold-catalyzed intermolecular alkyne oxidation
He, Weimin,Li, Chaoqun,Zhang, Liming
supporting information; experimental part, p. 8482 - 8485 (2011/07/08)
The first efficient intermolecular reaction of gold carbene intermediates generated via gold-catalyzed alkyne oxidation has been realized using nitriles as both the reacting partner and the reaction solvent, offering a generally efficient synthesis of 2,5-disubstituted oxazoles with broad substrate scope. The overall reaction is a [2 + 2 + 1] annulation of a terminal alkyne, a nitrile, and an oxygen atom from an oxidant. The reaction conditions are exceptionally mild, and a range of functional groups are easily tolerated. With complex and/or expensive nitriles, only 3 equiv could be sufficient to achieve serviceable yields in the absence of any solvent and using only 1 mol % BrettPhosAuNTf2 as the catalyst.
Hypervalent iodine(III) mediated synthesis of 2-substituted-5-aryloxazoles
Kang, Iou-Jiun,Wang, Huey-Min,Lin, Mei-G,Chen, Ling-Ching
, p. 1031 - 1034 (2007/10/03)
A direct and efficient method for the preparation of 2-substituted-5- aryloxazoles was realized by reaction of aryl methyl ketones with various nitriles in the presence of phenyliodine(III) triflate.
A facile one-pot synthesis of 2,5-disubstituted oxazoles using iodobenzene diacetate
Varma, Rajender S.,Kumar, Dalip
, p. 1533 - 1534 (2007/10/03)
A facile one-pot synthesis of oxazoles 1a-h is described that utilizes readily available aromatic α-methyl ketones and a safe hypervalent iodine reagent, iodobenzene diacetate.
A novel and direct synthesis of 2-alkyl-5-aryl disubstituted oxazoles
Lee, Jong Chan,Hong, Taiyoung
, p. 8959 - 8960 (2007/10/03)
A direct and efficient method for the preparation of 2-alkyl-5-aryl disubstituted oxazoles was realized by reaction of aromatic α-methyl ketones with various aliphatic nitriles in the presence of T1(OTf)3.
A New Versatile Synthesis of Oxazoles by Intramolecular Aza-Wittig Reaction
Takeuchi, Hisato,Yanagida, Shun-ichi,Ozaki, Tooru,Hagiwara, Satoshi,Eguchi, Shoji
, p. 431 - 434 (2007/10/02)
A new synthesis of oxazoles by an intramolecular aza-Wittig reaction is described.Readily available α-azido ketones 2 were converted to (Z)-β-(acyloxy)vinyl azides 3 by selective enol acylation.These vinyl azides 3 reacted with triethyl phosphite to afford the corresponding oxazole derivatives 5 via the Staudinger reaction, followed by an intramolecular aza-Wittig reaction.In particular, this oxazole synthesis was useful for oxazoles having acid-labile substituents.
THE BF3-CATALYZED DECOMPOSITION OF DIAZO CARBONYL COMPOUNDS IN NITRILES. FORMATION OF ENAMIDES
Ibata, Toshikazu,Yamamoto, Masahiko
, p. 161 - 164 (2007/10/02)
The BF3-catalyzed decomposition of α-diazoacetophenones in acetonitrile, propionitrile, or methyl thiocyanate in the presence of 1,3,5-trimethoxybenzene produced enamides (7) in good yield.
Lewis Acid Promoted Reactions of Diazocarbonyl Compounds. 3. Synthesis of Oxazoles from Nitriles through Intermediate β-Imidatoalkenediazonium Salts
Doyle, Michael P.,Buhro, William E.,Davidson, James G.,Elliott, Robert C.,Hoekstra, James W.,Oppenhuizen, Mark
, p. 3657 - 3664 (2007/10/02)
Lewis acid promoted reactions of α-diazocarbonyl compounds with nitriles provide a general method for the production of oxazoles in high isolated yields.The generality of this method is evaluated by the effectiveness of oxazole formation in surveys of Lewis acids, diazocarbonyl compounds, and nitriles.Because of the relative absence of α-halogenation products in reactions performed with BF3*Et2O, this Lewis acid is preferred when the nitrile is employed as the reaction solvent.Reactions of diazo ketones in nitrile solvents generally result in higher oxazole yields(70-99percent) than do reactions of ethyl diazoacetate (26-31percent).When these transformations are performed at or below room temperature, at least 1 equiv of the Lewis acid is required, although catalytic activity is observed in reactions performed at 65 deg C.In BF3*Et2O promoted reactions, a minimum tenfold molar excess of nitrile is required for optimum oxazole production, although use of SbF5 results in high yields of oxazoles even when only a threefold excess of the nitrile is employed.The mechanism for oxazole formation is established as involving initial activation of the nitrile through association with the Lewis acid, followed by attack of the nitrilium complex at the carbonyl oxygen of the diazocarbonyl compound and internal displacement of nitrogen.Although Lewis acid association with the diazocarbonyl compound is the more favorable process in reactions performed with equivalent amounts of nitrile and diazocarbonyl compound, only equilibrium association of the Lewis acid with the nitrile effectively leads to oxazole formation.
