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Upstream product

• 273-53-0 benzoxazole 
• 4028-63-1 iodomesitylene 
• 1016769-45-1 N-(2-bromophenyl)-2,4,6-trimethylbenzamide 
• 487-68-3 mesytaldehyde 
• 95-55-6 2-amino-phenol 
• 271-89-6 1-benzofurane 
• 576-83-0 2,4,6-trimethylphenyl bromide 
• 5980-97-2 mesitylboronic acid 
• 480-63-7 mesitylenecarboxylic acid 
• 4170-90-5 2,4,6-trimethylbenzyl alcohol 
• 615-18-9 2-chloro-1,3-benzoxazole 
• 2633-66-1 2-mesitylmagnesium bromide 

Relevant academic research and scientific papers

Iron-catalyzed intramolecular O-arylation: Synthesis of 2-aryl benzoxazoles

(Chemical Equation Presented) A practical iron-catalyzed intramolecular O-arylation reaction and its application in the synthesis of benzoxazole derivatives, starting from the readily available 2-haloanilines, is presented. The key cyclization step involves the use of a combination of the cheap and environmentally friendly FeCl3 and 2,2,6,6-tetramethyl-3,5 heptanedione (TMHD) as the catalyst system.

Investigation of Pd-PEPPSI catalysts and coupling partners towards direct C2-arylation/heteroarylation of benzoxazole

2-Aryl/heteroaryl-substituted benzoxazoles are important heterocyclic motifs extensively found in several bioactive molecules, pharmaceuticals and natural products. In view of the importance of these compounds, there is need to develop easiest and simplest synthetic routes. The motive of this current work is to conduct the direct C2-arylation reaction on benzoxazole with various cross-coupling partners like aryl/heteroaryl halide/carboxylic acid/diazonium tetrafluoroborate/sulfonyl chloride/boronic acids in the presence of different symmetrical and unsymmetrical Pd-PEPPSI (pyridine-enhanced pre-catalyst preparation by stabilization initiation) catalysts via C (sp2)–C (sp2) bond formation. Compared with other coupling partners, boronic acids coupled with benzoxazole very efficiently in the presence of sterically and electronically tunable bulky1,3-bis(N,N′-2,4,6-triisopropylbenzyl)benzimidazolium-Pd-PEPPSI complex in open air to offer the corresponding C2-aryl/heteroaryl benzoxazole compounds. Further, it is worthy to mention that there is no need of any external oxidant/ligand/additive for the complete conversion of starting molecules to products. The reactions progressed successfully with a wide range of substrate scope and attained the products in good to excellent yields in a short reaction time in ethanol/water (1:1) medium. Greatly, catalysts can be recovered and reused for few cycles with significant reactivity.

Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling

Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.

Visible Light-Induced Copper-Catalyzed C—H Arylation of Benzoxazoles?

A general method for visible light-induced copper-catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron-poor heterocycles such as thiophene possessing one electron-withdrawing group can also be arylated.

Continuous flow/waste-minimized synthesis of benzoxazoles catalysed by heterogeneous manganese systems

Herein, we present our results on the development of a waste minimized protocol for the synthesis of 2-arylbenzoxazoles in continuous flow. Manganese-based heterogeneous catalysts were used in combination with cyclopentylmethyl ether as an environmentally friendly and safe reaction medium. The use of oxygen promotes the oxidative process ensuring at the same time a complete regeneration of the catalyst adopting a flow configuration which does not include the use of an additional mechanical pump. These features allowed for a faster synthesis compared to batch procedures with minimal metal leaching.

Synthesis of Benzoxazoles Using Electrochemically Generated Hypervalent Iodine

The indirect ("ex-cell") electrochemical synthesis of benzoxazoles from imines using a redox mediator based on the iodine(I)/iodine(III) redox couple is reported. Tethering the redox-active iodophenyl subunit to a tetra-alkylammonium moiety allowed for anodic oxidation to be performed without supporting electrolyte. The mediator salt can be easily recovered and reused. Our "ex-cell" approach toward the electrosynthesis of benzoxazoles is compatible with a range of redox-sensitive functional groups. An unprecedented concerted reductive elimination mechanism for benzoxazole formation is proposed on the basis of control experiments and DFT calculations.

Chelating palladium complexes containing pyridine/pyrimidine hydroxyalkyl di-functionalized N-heterocyclic carbenes: Synthesis, structure, and catalytic activity towards C-H activation

The synthesis of novel chelating palladium complexes containing pyridine/pyrimidine hydroxyalkyl di-functionalized N-heterocyclic carbenes (NHCs) via direct metallation of the precursor imidazolium salts is presented. The structure has been characterized unambiguously by X-ray single crystal analysis. Catalytic activity investigation showed that the complexes catalyse the direct C-H bond arylation of (benzo)oxazoles efficiently when using tBuOLi as base and DMF as solvent.

Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: Enhancement of the reaction rate and selectivity by a base

An efficient visible-light-driven photocatalytic oxidation of various 2-substituted dihydropyrimidines and phenolic imines has been achieved using an organic photocatalyst eosin Y bis(tetrabutyl ammonium salt) (TBA-eosin Y) and inexpensive oxidant molecular oxygen. With the aid of a base, significantly enhanced photoinduced electron transfer from substrates dihydropyrimidines or phenolic imines to the excited state of TBA-eosin Y has enabled the aerobic oxidation to yield 2-(methylthio)pyrimidines or 2-arylbenzoxazoles selectively. This journal is the Partner Organisations 2014.

Kumada-Tamao-Corriu coupling of heteroaromatic chlorides and aryl ethers catalyzed by (IPr)Ni(allyl)Cl

The complex (IPr)Ni(allyl)Cl (IPr = 1,3-bis(2,6-diisopropylphenyl) imidazolidene) catalyzes the cross-coupling reactions of heteroaromatic chlorides with aryl Grignard reagents. Catalyst loadings as low as 0.1 mol % have been used to afford the products in excellent yields. This nickel-based catalytic system also promotes the activation of the CAr-O bond of anisoles in the Kumada-Tamao-Corriu reaction under fairly mild conditions.

Kumada coupling of aryl, heteroaryl, and vinyl chlorides catalyzed by amido pincer nickel complexes

A series of amido pincer complexes of nickel were examined for their catalysis in the Kumada cross-coupling reaction. The P,N,O-pincer nickel complexes tested are active catalysts for the cross-coupling of aryl, heteroaryl, and vinyl chlorides with aryl Grignard reagents. The reactions can proceed at room temperature and tolerate functional groups in aryl chlorides with the aid of LiCl and ZnCl2 additives (Figure presented).