5-phenyl-2- oxazole

Excited-state absorption spectra of p-phenylene-bis(5-phenyl-2-oxazole) (POPOP) in dioxan have been obtained over the spectral range 310—760 nm. In... 

The pH of the reaction stream was adjusted to neutral and the dark stream was washed with methyl-t-butyl ether to remove neutral organic impurities. The major impurity observed in the MTBE wash is phenyl oxazole formed by de-iodination of the starting iodoxazole. Phase separation of this wash is a difficult one due to the dark color of the reaction stream. 

Methyl-2-phenyl-oxazol-4-yl)ethoxy]benzo[2]thiophen-7-yl]methyl]-thiazolidine-2,4-dione. 

A microwave-assisted one-pot approach towards 2,4,5-trisubstituted oxazoles employed a hypervalent iodine (III) catalyst to bring about the reaction of ketones, 1,3-diketones and /3-keto-carboxylic acid derivatives with amides [75]. Microwave dielectric heating was also successfully utilized in a solid-supported, solvent-free synthesis of 2-phenyl-oxazol-5-ones (azlac-tones) [76] as well as in a solution phase synthesis of isomeric 2-phenyl-oxazol-4-ones (oxalactims) [77]. 

Phenyl oxazoles, (I), and 2,3,5-trisubstituted biphenyls, (II), prepared by Glom-bik (2) and Butera (3), respectively, were effective in treating metabolic disorders associated with insulin resistance. 

Methyl-2-phenyl-oxazole derivatives, (VI), (VII), and (VIII), prepared by Kuwabara (7), Fakhoury (8), and Tajima (9), respectively, were effective in the treatment of hyperlipidemia associated with Type II diabetes. 

Preparation of 5-(3-(2-(5-methyl-2-phenyl-oxazol-4-yl)ethoxy)benzyl)-2-phenyl-4-A-phenylamido-l, 2,3-triazole... 

A series of 2-aryloxazoloquinolones 32 having high affinity for the GABA receptor were prepared via a Pd-catalyzed intramolecular diaryl coupling of ethyl 5-bromo-2-phenyl-oxazole-4-carboxylate with 2-aminophenylboronic acid followed by cyclization [37]. This one-pot intramolecular Suzuki reaction was followed by cyclization to afford a tricyclic compound 32. 

EHphenyl ether is often used as a high-boiling solvent but it can take part in an intramolecular cyclization under some conditions. The reaction is rapid in the presence of a palladium salt (review [B-41]) and an acid such as methanesul-phonic or trifluoroacetic add or of boron trifluoride. Addition of 4-phenyl-oxazole to benzyne (generated from 1-aminobenzotriazole and LTA) is more eflSdent when both reagents are simultaneously introduced through two syringes on opposite sides of the reaction vessel. 

This method has afforded some 2-phenyl-4-(/3-aminoethyl)-, and 2-pheny 1-4- (/3-disubstituted-aminoethyl) oxazoles from benzamide and the appropriate substituted bromobutanones.90 A 5-oxazolylethanol derivative is obtained from the corresponding substituted a-chloro ketone and amide in the presence of calcium carbonate (to neutralize the generated hydrogen chloride.)91 Condensation of a-bromophenylacetaldehyde and p-bromo-benzamide at 110°-120° gives 50% yield of 2-p-bromophenyl-5-phenyl-oxazole.18... 

Changes in the electric dipole moments of 2-(l-naphthyl)-5-phenyl-oxazole and 2,5-bis(4-biphenylyl)oxazole between the ground and excited states have been measured in various solvents by absorption and fluo-... 

Oxalactims, for exanple 5//-methyl-2-phenyl-oxazol-4-one, were investigated as synthetically powerful synthons for the construction of a-hydroxy acids via o -deprotonation followed by molybdenum-catalyzed asymmetric allylation and a subsequent hydrolysis of the oxalactim rings. Among the series of the HMDS bases used in tbe Mo-catalyzed asymmetric allylation, LHMDS was found to be tbe base of choice providing better yields, regio- (branched/Unear), diastereo- andenantioselectivity than the corresponding allylation reactions mediated by KHMDS (eq 63). ... 

Dlmelhyl-2-thiophen-2-yl-oxazole 4,5-Dimethyl-2-phenyl-oxazole... 

Methyl-5-phenyl-oxazol 27 1217. 5-Methyl-2-phenyl-oxazol 27 I 218. Verbinduag C,oH30 aua l-Methyl-8-oxy-... 

Anhydro-hippimiunphenyleater, 5.Phen< oxy-2-phenyl-oxazol 9, 234, II178. 

Chlop.phenyl]-5-[4-methoxy-phenyl]-oxazol 27 II96. 

The reverse reactions of Diels-Alder reactions for thermal dissociations of cycloadducts in to dienes and dienophiles at higher temperatures or in the presence of Lewis acid or base are known as the retro-Diels-Alder (rDA) reactions. These reactions in most cases proceed in a concerted process. These reactions are often used for separation of diene or dienophile from their mixture with other compounds. Proper selection of conditions of these reactions provides new dienes and dienophiles, which are important synthons for synthesis of several bioactive natural products and organic molecules of complex structures. For example, the D-A adduct of 4-phenyl oxazole 110 with methyl acetylene dicarboxylate, on retro-D-A reaction gives new compounds, benzonitrile, and furan 3,4-dicarboxylic acid methyl ester 111 [65]. 

Miura et al. have described the nickel-catalyzed direct arylation of azoles with aryl bromides, using nickel(II) bromide or a nickel(II) bromide diglyme complex, in the presence of 1,10-phenanthroline as ligand, and lithium t-butoxide as base, in diglyme at elevated temperature. The systems were optimized for benzthiazoles, benzoxa-zoles, and 5-phenyl oxazoles benzthiazoles coupled efficiently without the addition of zinc to give 2-arylbenzthiazoles 3 (Scheme 5.1, Table 5.1). 

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