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The development of enantioconvergent cross-coupling of racemic alkyl halides directly with heteroarene C(sp2)?H bonds has been impeded by the use of a base at elevated temperature that leads to racemization. We herein report a copper(I)/cinchona-alkaloid-derived N,N,P-ligand catalytic system that enables oxidative addition with racemic alkyl bromides under mild conditions. Thus, coupling with azole C(sp2)?H bonds has been achieved in high enantioselectivity, affording a number of potentially useful α-chiral alkylated azoles, such as 1,3,4-oxadiazoles, oxazoles, and benzo[d]oxazoles as well as 1,3,4-triazoles, for drug discovery. Mechanistic experiments indicated facile deprotonation of an azole C(sp2)?H bond and the involvement of alkyl radical species under the reaction conditions.

A facile synthesis of 1,3,4-oxadiazoles and 1,3,4-oxadiazoles-d5 via [4 + 1] cyclization of ClCF2COONa with non-amine compounds containing amino groups is developed. Of note, this is the first time that halofluorinated compounds are used as C1 synthon to construct deuterated nitrogen-heterocyclic compounds. The current protocol features simple operation, readily accessible raw materials, wide substrate scope and valuable products

We report, herein, a palladium-catalyzed cascade comprising carbopalladation, 1,4-Pd-migration and C(sp2)?C(sp2) bond formation to construct a variety of bis-heterocyclic frameworks in a single operational step. The methodology provi

An efficient method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles and 1,3,4-thiadiazoles has been developed. Various hydrazides or thionyl hydrazides readily react with DMA derivatives in the presence of TiCl4 as a catalyst to afford the desired products. This protocol provides a simple and economical procedure that affords the target products with good yields and wide substrate scope.

A compound for use in the treatment of a disease ameliorated by the inhibition of Notum of formula (I): (I)

The invention discloses a method for constructing 2-p-methylphenyl-1,3,4-oxadiazole by taking DMF (N,N-dimethylformamide) as a carbon source at one step. The method comprises the following steps: taking p-methylbenzhydrazide as a reaction raw material; ta

An unprecedented Cu-catalyzed direct annulation of hydrazides with N,N-dimethylformamide (DMF) was developed, providing an efficient synthesis of valuable 1,3,4-oxadiazoles. This process features the short reaction time and can be safely conducted on gram scale. The reaction also facilitated the convenient synthesis of 1,3,4-oxadiazole-2(3H)-ones. Moreover, the mechanistic studies suggest that the source of CH is from the N-methyl group of DMF. (Figure presented.).

Palladium-catalyzed intramolecular carbopalladation onto allenamides completed by direct C-H allylation of heterocycles is studied. The domino construction/heteroarylation of isoquinolone process is first achieved. A general three-step one-pot strategy, i

A new and efficient method for the synthesis of 1,3,4-oxadiazoles via the annulation of hydrazides with benzene-1,3,5-triyl triformate (TFBen) under metal-free conditions is reported. A broad range of hydrazides were transformed into the corresponding 1,3

An I2-promoted, metal-free domino protocol for one-pot synthesis of 1,3,4-oxadiazoles has been developed via oxidative cleavage of C(sp2)-H or C(sp)-H bonds, followed by cyclization and deacylation. In this reaction, the use of K2CO3 as a base is found to be an essential factor in the cyclization and the C-C bond cleavage. This procedure proceeded smoothly in moderate to high yields with good functional group compatibility.

Three pyrene-oxadiazole derivatives were synthesized and characterized by optical, electrochemical, thermal, and theoretical investigations to obtain efficient multifunctional organic light emitting diode (OLED) materials. Synthesized molecules were used as emitters and electron transporters in three different device configurations, involving hole-injection/hole-blocking materials that showed good current and power efficiencies. To understand the underlying mechanisms involved in the application of these molecules as emitters and transporters, a detailed photophysical characterization of molecules 4-6 was carried out. The absorption, steady-state fluorescence, phosphorescence, fluorescence lifetime, and phosphorescence lifetime measurements were carried out. The high quantum yield and efficient reverse intersystem crossing leading to delayed fluorescence emission makes the molecule a good emitter, and the charge delocalization properties leading to excimer formation make them efficient electron transporters. Isoenergetic singlet and triplet states of the molecules make the reverse intersystem crossing feasible at room temperature even in the absence of thermal activation.

Transition-metal-free oxidative iodination of 2-substituted 1,3,4-oxadiazoles was achieved by using sodium iodide as the halide source and Selectfluor as the oxidant. Variously substituted products were obtained in moderate to good yields under operationa

A new strategy for the synthesis of 1,3,4-oxadiazoles was established through direct annulation of hydrazides with methyl ketones. It was found that the use of K2CO3 as a base achieves an unexpected and highly efficient C-C bond clea

Ultrasound promoted synthesis of 2-aryl-1,3,4-oxadiazoles at ambient temperature is reported. The remarkable features of the new procedure are shorter reaction time, excellent yields, cleaner reaction profile and simple experimental and workup procedure.

An efficient and inexpensive approach to the synthesis of 2-substituted and 2,5-disubstituted 1,3,4-oxadiazoles from arylhydrazides and orthoesters is reported using catalytic NH4Cl. The conditions are mild, and thus, compatible with a variety of functional groups. The optimized reaction is performed using 30 mol % of NH4Cl in 100% EtOH and is generally complete within 1 h for non-aromatic orthoesters and 2-10 h for aromatic orthoesters. The reaction permits both electron-releasing and electron-withdrawing groups on the arylhydrazide substrate. Most products are formed in high yields and require only minimal purification. Compared with earlier reports, the current reactions proceed in shorter time and require less of the orthoester.

The first direct oxidative coupling of 1,3,4-oxadiazoles with benzothiazoles has been accomplished using Pd(OAc)2 as a catalyst and Cu(OAc)2 as an oxidant. The similar combination of the catalyst and the oxidant has also been applied for direct arylation of 1,3,4-oxadiazoles with aryl boronic acids. Several novel oxadiazole derivatives have been prepared in high yields following both the methods.

No pressure: The oxidation of aromatic C-H bonds at room temperature was realized through a copper-catalyzed "oxygenase-type" oxidation of arenes and heteroarenes in the presence of air (see scheme). The reaction involves an oxygen-atom transfer from O2 in the air onto the substrates. Copyright

The first direct C-H alkenylation of 1,3,4-oxadiazoles with trans-β-halo olefinic system has been carried out using a combination of CuI/DMEDA as a catalyst. A wide range of 2-E-vinyl-substituted oxadiazoles were obtained in high yields (85-93%).

The direct C-H alkynylation of 1,3,4-oxadiazoles with 1,1-dibromo-1-alkenes has been accomplished by using a combination of CuBr/LiOtBu in PEG-400 (a green solvent) at 80 °C. The products were formed in high yields (73-86%) in 2 h. No additional ligand or volatile solvent was required and the conversion was ecofriendly. The direct C-H alkynylation of 1,3,4-oxadiazoles with 1,1-dibromo-1-alkenes has been accomplished by using a combination of CuBr/LiOtBu in PEG-400 (a green solvent) at 80 °C. The products were formed in high yields (73-86%) in 2 h. No additional ligand or volatile solvent was required and the conversion was ecofriendly. Copyright

A convenient transition metal-free procedure for the direct thiolation of 1,3,4-oxadiazole C-H bonds using diaryl disulfides has been developed. Other substrates including indole, benzothiazole, N-phenylbenzimidazole, and caffeine were also thiolated in this manner, providing the corresponding products in good to excellent yields. This journal is

Three series of substituted 1,3,4-oxadiazoles were studied by 17O NMR spectroscopy. Chemical shifts values were correlated with empirical Hammett parameters as well as calculated bond lengths and chemical shielding values.

The reactions of benzoic acid derivatives with (N-isocyanimino)triphenylphosphorane proceed smoothly at room temperature to afford 2-aryl-1,3,4-oxadiazoles in high yields.

15N NMR chemical shifts of 2-aryl-1,3,4-oxadiazoles were assigned on the basis of the 1H-15N HMBC experiment. Chemical shifts of the nitrogen and carbon atoms in the oxadiazole ring correlate with the Hammett σ-constants of substituents in the aryl ring (r2 ≥ 0.966 for N atoms). 15N NMR data are a suitable and sensitive means for characterizing long-range electronic substituent effects. Additionally, 13C NMR data for these compounds are presented. Copyright