68395-81-3Relevant academic research and scientific papers
Synthesis of 2,5-Disubstituted Oxazoles from Arylacetylenes and α-Amino Acids through an i 2 /Cu(NO 3) 2 ?3H 2 O-Assisted Domino Sequence
Wang, Jungang,Cheng, Yan,Xiang, Jiachen,Wu, Anxin
supporting information, p. 743 - 747 (2019/03/26)
A new strategy has been developed for the synthesis of 2,5-disubstituted oxazoles from easily available arylacetylenes and α-amino acids in the presence of Cu(NO 3) 2 ?3H 2 O and iodine. This reaction process involves the I 2 /Cu(NO 3) 2 ?3H 2 O-assisted transformation of arylacetylene to α-iodo acetophenone, Kornblum oxidation to phenylglyoxal, condensation to imine, decarboxylation/annulation/oxidation reaction sequence to approach 2,5-disubstituted oxazoles.
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.
N-heterocyclic carbene-Pd(II)-1-methylimidazole complex catalyzed C-H bond benzylation of (benzo)oxazoles with benzyl chlorides
Ji, Ya-Yun,Zhang, Yu,Hu, Yuan-Yuan,Shao, Li-Xiong
, p. 6818 - 6823 (2015/08/24)
The first example of phosphine-free, NHC-Pd(II) complex catalyzed direct C-H bond benzylation of (benzo)oxazoles with benzyl chlorides was reported in this paper. Under the suitable conditions, all reactions worked well enough to give the desired C2-benzylated products in good to almost quantitative yields, providing a facile and straight pathway for the C-H bond benzylation of (benzo)oxazoles within short time.
Synthesis of oxazoles through copper-mediated aerobic oxidative dehydrogenative annulation and oxygenation of aldehydes and amines
Xu, Zejun,Zhang, Chun,Jiao, Ning
supporting information, p. 11367 - 11370 (2013/01/15)
A fragment-assembling strategy is used to form oxazoles from aryl acetaldehydes, amines, and molecular oxygen under mild conditions (see scheme). The transformation is highly efficient with the removal of six hydrogen atoms, including the cleavage of four C(sp3)-H bonds. Copyright
Palladium-catalyzed direct benzylation of azoles with benzyl carbonates
Mukai, Tomoya,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
supporting information; scheme or table, p. 1360 - 1363 (2010/05/19)
"Chemical Equation Presented" The direct aromatic sp2 C-H benzylation of azole compounds with benzyl carbonates proceeds efficiently in the presence of a Pd2(dba)3/dppp catalyst system and KaOAc as a base to afford the corresponding diarylmethanes in good yields. In addition, the same palladium catalyst enables the direct benzylic sp3 C-H benzylation with the second benzyl carbonates without employing any external base.
One-pot Friedel-Crafts/Robinson-Gabriel synthesis of oxazoles using oxazolone templates
Keni, Manasi,Tepe, Jetze J.
, p. 4211 - 4213 (2007/10/03)
We report herein a one-pot synthesis of 2,4,5-trisubstituted oxazoles via a Friedel-Crafts/Robinson-Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted oxazoles in good yields.
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.
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.
