2549-31-7Relevant academic research and scientific papers
NOVEL DEHYDROGENATION OF 2,5-DIARYLSUBSTITUTED Δ2-OXAZOLINES TO OXAZOLES
Klein, Robert F. X.,Horak, Vaclav,Baker, Godfrey A. S.
, p. 1631 - 1635 (1993)
The dehydrogenation of various 2,5-diaryl substituted Δ2-oxazolines with either Br2/LiBr/CaCO3 (molar ratio 1.05 : 2 : 3) or CuBr2/LiBrCaCO3 (2 : 1 :3) in refluxing o-dichlorobenzene gives the corresponding oxazole in up to 87percent yield.Free radical benzylic bromination followed by dehydrobromination is the expected dehydrogenation mechanism.The successful application of the reagent combination for this transformation is in contrast to standard dehydrogenation reagents, including N-bromosuccinimide, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, chloranil, NiO2 and active γ-MnO2.
CO2/Photoredox-Cocatalyzed Tandem Oxidative Cyclization of α-Bromo Ketones and Amines to Construct Substituted Oxazoles
Zhang, Xiaowei,He, Yonghui,Li, Jing,Wang, Rui,Gu, Lijun,Li, Ganpeng
, p. 8225 - 8231 (2019/06/17)
CO2/photoredox-cocatalyzed tandem oxidative cyclization of α-bromo ketones and amines for the preparation of substituted oxazoles has been achieved. The avoidance of using both transition-metal catalysts and peroxides makes this method more sustainable and renewable.
Alkynyl Thioethers in Gold-Catalyzed Annulations To Form Oxazoles
Reddy, Raju Jannapu,Ball-Jones, Matthew P.,Davies, Paul W.
supporting information, p. 13310 - 13313 (2017/10/07)
Non-oxidative, regioselective, and convergent access to densely functionalized oxazoles is realized in a functional-group tolerant manner using alkynyl thioethers. Sulfur-terminated alkynes provide access to reactivity previously requiring strong donor-substituted alkynes such as ynamides. Sulfur does not act in an analogous donor fashion in this gold-catalyzed reaction, thus leading to complementary regioselective outcomes and addressing the limitations of using ynamides.
Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid
Yamada, Kohei,Kamimura, Naoto,Kunishima, Munetaka
, p. 1478 - 1485 (2017/08/02)
A novel method for the synthesis of trisubstituted oxazoles via a one-pot oxazole synthesis/Suzuki–Miyaura coupling sequence has been developed. One-pot formation of 5-(triazinyloxy)oxazoles using carboxylic acids, amino acids and a dehydrative condensing reagent, DMT-MM, followed by Ni-catalyzed Suzuki–Miyaura coupling with boronic acids provided the corresponding 2,4,5-trisubstituted oxazoles in good yields.
One-pot preparation of 2,5-disubstituted and 2,4,5-trisubstituted oxazoles from aromatic ketones with molecular iodine, oxone, and trifluoromethanesulfonic acid in nitriles
Imai, Sho,Kikui, Hiroki,Moriyama, Katsuhiko,Togo, Hideo
, p. 5267 - 5274 (2015/07/15)
Alkyl aryl ketones were successfully converted into the corresponding 2,5-disubstituted and 2,4,5-trisubstituted oxazoles in good to moderate yields in a one-pot manner, utilizing iodine, Oxone, and trifluoromethanesulfonic acid in nitriles under transition-metal-free conditions. The present method could be used for the preparation of Oxaprozin from benzyl phenyl ketone and succinonitrile. A possible reaction mechanism was proposed in which the key intermediates were α-iodoalkyl aryl ketones and α-iodosylalkyl aryl ketones.
Practical oxazole synthesis mediated by iodine from α-bromoketones and benzylamine derivatives
Gao, Wen-Chao,Wang, Ruo-Lin,Zhang, Chi
, p. 7123 - 7128 (2013/10/22)
The reagent system of I2/K2CO3 could efficiently promote the oxazole synthesis from α-bromoketones and benzylamine derivatives in DMF. This method was not only suitable for 2,5-diaryl oxazole synthesis but also for 2,4,5-trisubstituted oxazole and 5-alkyl/alkenyl oxazole synthesis. Furthermore, this method was successfully applied to a one-step synthesis of a natural product halfordinol in 62% yield.
Zn(OTf)2-catalyzed cyclization of proparyl alcohols with anilines, phenols, and amides for synthesis of indoles, benzofurans, and oxazoles through different annulation mechanisms
Kumar, Manyam Praveen,Liu, Rai-Shung
, p. 4951 - 4955 (2007/10/03)
Zn(OTf)2 (10 mol %) catalyzed the cyclization of propargyl alcohols with PhXH (X = O, NH) in hot toluene (100 °C) without additive and gave indole and benzofuran products with different structures. In such transformations, α-carbonyl intermedia
Synthesis of 2,4,5-Trisubstituted Oxazoles
Cai, Xiao-hua,Yang, Hai-jun,Zhang, Guo-lin
, p. 1569 - 1571 (2007/10/03)
2,4,5-Trisubstituted oxazoles were synthesized in good yields starting from α-methylene ketones by nitrosation, condensation with aldehydes and reduction with zinc in acetic acid at 40 deg C. (5-Methyl-2-phenyloxazol-4-yl)ethanol was prepared by reduction of ethyl (5-methyl-2-phenyloxazol-4-yl)acetate with LiAlH4.
Cyclocondensations of amidophenacylation products of triphenylphosphoranylideneacetonitrile
Panchishin,Smolii,Chernega,Rusanov,Drach
, p. 518 - 522 (2007/10/03)
When heated in polyphosphoric acid, the products of amidophenacylation of the available triphenylphosphoranylideneacetonitrile undergo the Robinson-Gabriel cyclization followed by other transformations. Treatment of the resulting mixture with sodium perch
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.
