Oxazole Research Articles

SYNTHESIS AND APPLICATION OF AZACYCLOALK-1-ENE-FUSED OXAZOL-3-IUM SALTS

Synthesis and application of azacycloalk-1-enefused oxazol-3-ium salts are summarized. The microreview covers all synthetic methods for obtaining 6,7-dihydro-5H-pyrrolo[2,1-b]oxazol-4-ium and 5,6,7,8-tetrahydrooxazolo[3,2-a]pyridin-4-ium derivatives that have been classified in two distinct categories: cyclization leading to the formation of azacycloalk-1-ene ring and cyclization leading to the formation of oxazole ring. Application of these azacycloalk-1-enefused oxazol-3-ium salts has been discussed.

DECORATION OF 1,3-OXAZOLE BY ALKYL SUBSTITUENTS V IA CH ACTIVATION

Microreview describes recent advances in the synthesis of alkyl-substituted 1,3-oxazoles via CH activation reaction. The latest selected examples (2008–2018) on the synthesis of alkyl-substituted oxazoles by transition metal-catalyzed CH activation reactions as well as metalation with subsequent alkylation are summarized.

Synthesis of Naphthoxazoles by Photocyclization of 4‐/5‐(Phenylethenyl)oxazoles

Promising test results on the biological activity of our previously described naphtho[1,2‐d]oxazoles and heterobenz[1,2‐d]oxazoles, obtained by the photochemical cyclization of 5‐phenylethenyl‐ and 5‐heteroarylethenyloxazoles, prompted us to continue with the photochemical synthesis of substituted naphtho[1,2‐d]oxazoles, and to extend the photochemical cyclization to the synthesis of naphtho/heterobenz[2,1‐d]oxazoles from 4‐(aryl/heteroarylethenyl)oxazoles. The required p‐ and o‐phenyl‐substituted 5‐arylethenyloxazoles were prepared from the corresponding α,β‐unsaturated aldehydes and the TosMIC reagent (tosylmethyl isocyanide) by the Van Leusen reaction. The substituted 4‐(aryl/heteroarylethenyl)oxazoles were prepared by the Wittig reaction starting from various phosphonium salts and 2‐H/methyl‐4‐oxazolecarbaldehydes.

Synthesis of 2,5-Disubstituted Oxazoles

Key words cycloaddition - isocyanides - oxazoles - methyl ketones

Synthesis and Insecticidal Activity of o-Carboxamidobenzamide Compounds Containing 2-(Substituted phenyl)oxazole Group

为了研究邻甲酰胺基苯甲酰胺类化合物的杀虫活性，总结该类化合物的构效关系、合成高活性化合物，以2-氨基-3-羟基丙酸与取代2-硝基苯甲酸为原料，经过酯化反应、缩合反应、硝基还原反应、三光气缩合反应等一系列步骤，合成了29个2-（取代苯基）噁唑基的邻甲酰胺基苯甲酰胺类目标化合物，产率在30%~50%之间.根据离体杀东方粘虫活性测定实验结果可知，该类化合物对东方粘虫表现出一定的杀虫活性，其中目标化合物2-（2-溴苯基）- N -（4-氯-2-甲基氨基甲酰基-6-甲基苯基）噁唑-4-甲酰胺（ 11p ）活性最高.通过对目标化合物的结构与杀虫活性的分析，总结出该类化合物的构效关系，筛选出了较高活性的目标化合物.

RECENT ADVANCES IN THE SYNTHESIS AND APPLICATIONS OF OXAZOLO[5,4- d ]PYRIMIDINES

Modern methods of synthesis of oxazolo[5,4- d ]pyrimidines published over the past 10 years are reviewed in the present communication. The two main approaches include the synthesis via cyclization of pyrimidine derivatives resulted in the fused oxazole ring or by condensation of oxazole derivatives leading to fused pyrimidine rings.

Design, Synthesis and Biological Activity of Novel Substituted Phenyl Oxazol Based Compounds†

Several famous bioactive heterocycles such as oxazole,imidazolidine and thiazolidine are widely used in both pharmaceutical and pesticide industry. To find new lead compounds with favorable biological activities,a series of novel substituted phenyl oxazol based compounds containing 2-nitroaminoimidazoline or thiazolidine was designed via the method of linking active sub-structures. The target compounds were synthesized from substituted benzoic acid in three steps. Their structures were confirmed by1H NMR and elemental analysis. The preliminary bioassay results indicated that some target compounds showed obvious inhibitory activities against Gibberella saubinetii,Rhizoctonia solani,Botrytis cinerea and Alternaria solan. Especially,compound 5q,with 62% and 86% inhibition rate against Gibberella saubinetii and Botrytis cinerea,respectively, exhibited equivalent activity to Polyoxin B with 57% and 85% inhibition rate at a concentration of 100 μg/mL. The structure-activity relationship indicated that the type and position of substituent on the benzene ring would influence the activity obviously. The halogen substituent was favorable to activity. Besides,compounds with ortho-substituent showed better activity than those with meta or para-substituent.

PhI(OCOCF3)2-Mediated Synthesis of 2-(Trifluoromethyl)oxazoles

Key words 2-(trifluoromethyl)oxazoles - phenyliodine bis(trifluoroacetate) - enamines

ChemInform Abstract: Benzoxazoles and Other Annulated Oxazoles

AbstractReview: 219 refs.

Gold-Catalyzed [2+2+1] Synthesis of 2,5-Disubstituted Oxazoles

Reported is the synthesis of 2,5-disubstituted oxazoles 3 via the gold-catalyzed oxidation of alkynes 1 followed by reaction with ­nitriles 2. Due to the mild reaction conditions, a broad range of functional groups are tolerated on the alkyne component, including aldehydes, halides, protected amines, alcohols, and thiols. Both aliphatic and aromatic alkynes participate equally well in the reaction. The nitrile is typically used as the solvent (0.1 M concentration). However, for expensive nitriles, only three equivalents are sufficient to obtain decent yields in the absence of another solvent (using 1 mol% BrettPhosAuNTf2 as catalyst).

ChemInform Abstract: Synthesis of 2,4-Disubstituted Oxazoles.

ChemInform Abstract: Synthesis of 2,4-Disubstituted Oxazoles.

ChemInform Abstract: Synthesis of Luminophoric Derivatives of PBD Based on 2,5-Diaryl Substituted Thiazoles and Oxazoles.

ChemInform Abstract: Synthesis of Luminophoric Derivatives of PBD Based on 2,5-Diaryl Substituted Thiazoles and Oxazoles.

Potassium Carbonate, a Support for the Green Synthesis of Azoles and Diazines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Functionalized Oxazolines and Oxazoles with DAST and Deoxo-Fluor

Synthesis of Functionalized Oxazolines and Oxazoles with DAST and Deoxo-Fluor

Potassium carbonate, a support for the green synthesis of azoles and diazines

AbstractA novel potassium carbonate mediated synthesis of 2‐amino‐1,3‐thia/oxa zoles, 2‐amino‐1,3,4‐thia/oxa diazines and 2‐hydrazino‐1,3,4‐thiadiazines has been described here. The use of K2CO3 allows for an aqueous workup thereby eliminating the organic solvent from both the reaction step and post reaction stage, without compromising the yield and reaction time.

Oxazoles based on 2-amino-3-hydroxyphenalenone

Oxazoles based on 2-amino-3-hydroxyphenalenone

Spectroscopic studies of single-stranded DNA ligands and oxazole yellow dyes.

Interactions between short single-stranded DNA ligands and fluorescent DNA indicator dyes were used to investigate binding selectivity of the ligands. Conformational differences among four DNA ligands of different sequence and structure, including two that form a G-quartet and two that do not, were confirmed by circular dichroism spectroscopy. Their interactions with indicator dyes YO-pro-1 iodide (YO) and YOYO-1 iodide (YOYO) were probed using measurements of dye absorbance; induced circular dichroism; and fluorescence spectra, anisotropy, and lifetime. Equilibrium binding constants and stoichiometry were determined as well. Results indicate significant differences among the dye interactions and binding stoichiometries of the four ligands. One of the G-quartet forming ligands, a 20-mer of sequence 5'-GGTTTTGGTTTTGGTTTTGG-3', shows distinctly different interactions from the other three ligands, all of which are 15-mers. These studies illustrate the importance of sequence and conformation in determining the binding interactions of short single-stranded DNA.

A New Route to Functionalised Oxazoles

A New Route to Functionalised Oxazoles

Synthesis and Reactions of Lithiated Monocyclic Azoles Containing Two or More Hetero-Atoms. Part II: Oxazoles

Synthesis and Reactions of Lithiated Monocyclic Azoles Containing Two or More Hetero-Atoms. Part II: Oxazoles

Study of The Diazoimine/Triazole Equilibria for Substituted Oxazoles and Oxadiazoles

Study of The Diazoimine/Triazole Equilibria for Substituted Oxazoles and Oxadiazoles