Search

Promoted by K2CO3 (2.0 equiv), the 1,3-dipolar [3+3] cy­cloaddition between 1, 4-benzodiazepinone-based nitrones and α-halohydroxamates processed smoothly under the mild reaction conditions and delivered structurally novel and complex cis- or trans-configured d-edge heterocycle-fused 1,4-benzodiazepinones in up to >99% isolated yield with >20:1 dr. The relative configuration of the title chemical entities was clearly identified with the use of single-crystal X-ray structure analysis. The reaction mechanism was assumed to interpret the diastereoselective production of the obtained cis- or trans-configured d-edge heterocycle-fused 1,4-benzodiazepinones.

In the presence of Na2CO3, conjugate addition of α-halo hydrazones to nitroso compounds proceeded readily to give polyfunctionalized nitrones in reasonable chemical yields and excellent stereoselectivities. The chemical structure and the stereochemical configuration of the products were unambiguously identified by an X-ray single-crystal structural analysis.

Under the catalysis of PhCO2H, the 1,3-dipolar [3+2] cyclo­addition between pyrazolone-based olefins and N,N′-cyclic azomethine imines proceeded readily, thus delivering structurally novel spiropyrazolones with up to 98% yield and >20:1 dr. The relative stereochemical configuration of the obtained spiropyrazolones was unambiguously ­assigned by X-ray single-crystal structure analysis. The diastereoselective formation of the title spiropyrazolones was interpreted by the hypothesized reaction mechanism.

Under the reaction conditions of Pd(PPh3)4 (2.5 mol %) and PPh3 (10 mol %) in EtOAc at 60 °C, the formal (5 + 6) cycloaddition of vinylethylene carbonates with isatoic anhydrides proceeded smoothly and furnished medium-sized N,O-containing heterocycles in reasonable chemical yields. The chemical structures of the title products were clearly identified by X-ray diffraction analysis.

Under the catalysis of Pd2(dba)3·CHCl3/(±)-L5, the three-component decarboxylative coupling reactions among alkylidene pyrazolones, allyl carbonates and active methylene compounds furnished the desired products in acceptable chemical yields.

In the presence of Pd2(dba)3·CHCl3 (2.5 mol%), PPh3 (10 mol%), and 60% NaH (1.5 equiv), the formal [5+3] cycloaddition between isatin-based α-(trifluoromethyl)imines and vinyloxiranes proceeded readily in 1,2-DCE at 40 ℃ and afforded cis-configured medium-heterocycle-fused spirooxindoles in the reasonable chemical yields with >20:1 dr. The relative stereochemical configuration of the title products was identified by X-ray diffraction analysis.

Under the reaction conditions of Pd(PPh

Chirality, an intrinsic degree of freedom, has been barely exploited as the information carriers in data transmission, processing, computing, etc. Recently the magnons in antiferromagnets were proposed to carry both right-handed and left-handed chiralities, shedding a light on chirality-based spintronics in which chirality-based computing architectures and chiral magnonic devices may become feasible. However, the practical platform for chirality-based spintronics remains absent yet. Here we report an artificial ferrimagnetic Py/Gd/Py/Gd/Py/Pt multilayer by which the switching, reading, and modulation of magnon chirality are demonstrated. In particular, the coexisting resonance modes of ferromagnetic and antiferromagnetic characteristics permit the high adjustability and easy control of magnon chirality. As a main result, we unambiguously demonstrated that Py precessions with opposite chiralities pump spin currents of opposite spin polarizations into the Pt layer. Our result manifests the chirality as an independent degree of freedom and illustrates a practical magnonic platform for exploiting chirality, paving the way for chirality-based spintronics.

A mild, catalyst- and metal-free photochemical protocol for the oxygenation of 3-cyano-1,4-dihydropyridines to 5-cyano-2-pyridones was developed. Utilizing molecular oxygen from the air as the oxidant and a cheap blue LED lamp as the light source, a variety of 3-cyano-1,4-dihydropyridines were converted into the corresponding 5-cyano-2-pyridones in moderate to excellent yields. Exploration of the substrate scope revealed that 3-cyano and 4-aryl groups play an important role in the formation of 2-pyridone.

In the presence of PhI(OH)(OTs) and NaH, the diastereoselective formal [3 + 3] cycloaddition of isatin-based α-(trifluoromethyl)imines with N,N′-dialkyloxyureas proceeded readily, and furnished the relatively trans-configured novel spiro-1,3,5-triazinan-2-ones in reasonable chemical yields. The relative stereochemical configuration of the target products was clearly identified by X-ray diffraction analysis.

Under the catalysis of chiral palladium(0)/ligand complex, the [4 + 2] cycloaddition between vinyl benzoxazinanones and barbiturate-based olefins proceeded readily and provided barbiturate-fused spirotetrahydroquinolines in up to 96% chemical yield with up to >99:1 dr and 97% ee. The absolute configuration of barbiturate-fused spirotetrahydroquinolines was clearly identified by X-ray single crystal structure analysis. The reaction mechanism was proposed to shed light on the enantioselective formation of barbiturate-fused spirotetrahydroquinolines.

Under the catalysis of Pd2(dba)3 (2.5 mol%), PPh3 (10.0 mol%) and TMSCl (1.0 eq.), the formal [5+2] cycloaddition of vinylethylene carbonates to oxazol-5-(4H)-ones proceeded readily in THF at 60 °C to r.t., thus furnishing 3,4-dihydrooxepin-2(7H)-ones in 67-99% chemical yields. The chemical structure of one compound was confirmed by X-ray diffraction analysis, and the others were suggested by inference.

In the presence of Na2CO3, the [3+2] cycloaddition of azaoxyallyl cations in situ formed from α-halohydroxamates with isothiocyanides proceeded smoothly and furnished (Z)-2-iminothiazolidin-4-ones in 25-99% chemical yields. The chemical structure of title compounds was firmly confirmed by an X-ray single crystal structure analysis.

Catalyzed by 10 mol % of PhCO2H, the [3+2] cycloaddition between 3-isothiocyanato oxindoles and nitroso compounds proceeded readily, and delivered novel 1,2,4- oxadiazolidine-3-thione-fused spirooxindoles in 40-82% chemical yields. The chemical structure of the title compounds was firmly confirmed by an X-ray single crystal structure analysis.

In the presence of sodium carbonate, the [4 + 2] cycloaddition of α-halogeno hydrazones to imines proceeded readily, and furnished 2,3,4,5-tetrahydro-1,2,4-triazines in moderate to high chemical yields.

Promoted by Et3N, the 1,3-dipolar [3 + 3] cycloaddition of α-halohydroxamate-based azaoxyallylcations with hydrazonoyl chloride-derived nitrile imines occurred efficiently, and furnished desired products in acceptable chemical yields. The chemical structure of the title compounds was firmly confirmed by an X-ray single crystal structure analysis.

In the presence of Na2CO3, azaoxyallyl cations in situ generated from α-halohydroxamates with nitrones readily underwent [3 + 3] cycloaddition, and gave rise to 1,2,4-oxadiazinan-5-one derivatives in 56–99% chemical yields. The chemical structure of the title compounds was unambiguously identified by X-ray single crystal structure analysis.

In the presence of TMSCl, the [3 + 2] cycloaddition of oxazol-5-(4H)-ones with nitrones proceeded smoothly and furnished the desired isoxazolidin-5-ones with high diastereoselectivities in reasonable chemical yields. The chemical structure of the title compounds was firmly confirmed by X-ray single-crystal structure analysis.

Catalyzed by a Cinchona-based thiourea, the [3+2] cycloadditions of barbiturate-based olefins with 3-isothiocyanatooxindoles proceeded readily, and furnished dispirobarbiturates in excellent chemical yields with excellent diastereo- and enantioselectivities. The absolute configuration of dispirobarbiturates was firmly confirmed by an X-ray single crystal structure analysis. A reaction mechanism was proposed to account for the enantioselective formation of dispirobarbiturates.

In the presence of 10 mol% of Na2CO3, the desired imidazolidine-spirooxindoles were obtained in 81–99% yield with up to 99 : 1 dr by means of the diastereoselective [3 + 2] cycloaddition of N-acylhydrazine-derived imines with 3-isothiocyanato oxindoles. Single-crystal X-ray structure analysis was conducted to determine the relative stereochemistry of the imidazolidine-spirooxindoles. Diastereoselective access to the imidazolidine-spirooxindoles was hypothesized by the proposed mechanism.

In the presence of K2CO3, the [4 + 2] cycloaddition of α-halogeno hydrazones with azodicarboxylic acid derivatives proceeded efficiently, and delivered novel non-aromatic 1,2,3,6-tetrahydro-1,2,3,4-tetrazines in moderate to excellent chemical yields.

Under mild reaction conditions, the tandem cycloadditions of cyclic N-sulfonylimines with in situ generated Huisgen 1,4-dipoles from dialkyl acetylenedicarboxylates and pyridines underwent readily, and delivered highly functionalized polycyclic 1,2,3,4-tetrahydropyrimidine-fused benzosultams in low to excellent chemical yields with excellent diastereoselectivities.

Under catalysis of 10 mol % of Et3N, the [3 + 2] cycloaddition of barbiturate-based olefins with 3-isothiocyanato oxindoles underwent smoothly and afforded the desired dispirobarbiturates in up to 99% yield with up to 99:1 dr. The relative configuration of the dispirobarbiturates was unambiguously determined by X-ray single-crystal structure analysis. The reaction mechanism was proposed to shed light on the diastereoselective formation of the dispirobarbiturates.

In the presence of a Cinchona alkaloid-based squaramide organocatalyst, the [3+2] cycloaddition of isatin-derived azomethine ylides with maleimides proceeded readily, thus delivering the desired pyrrolidine-fused spirooxindoles in 61–89% yields with >20:1 dr and 12 to >99 % ee. The absolute configuration of 5-chloro-1,5′-dimethyl-3′-phenyl-3′,3a′-dihydro-2′H-spiro[indoline-3,1′-pyrrolo[3,4-c]pyrrole]-2,4′,6′(5′H,6a′H)-trione was unambiguously determined by means of X-ray single crystal structure analysis. The reaction mechanism was hypothesized to account for the enantioselective formation of 5-chloro-1,5′-dimethyl-3′-phenyl-3′,3a′-dihydro-2′H-spiro[indoline-3,1′-pyrrolo[3,4-c]pyrrole]-2,4′,6′(5′H,6a′H)-trione.

In the presence of cinchona-thiourea organocatalyst C1, the developed organocatalytic three-component cascade reaction of isatins, malononitrile, and 2-hydroxynaphthalene-1,4-diones readily proceeded to furnish chiral pyranonaphthoquinone-fused spirooxindoles in excellent chemical yields and high enantioselectivities (up to 99 % yield and 97 % ee). The absolute configurations of the spirooxindoles were assigned on the basis of an X-ray single crystal structure. Moreover, a reaction mechanism is proposed that accounts for the stereocontrolled formation of the chiral spirooxindoles,.

In the presence of Et3N, the [3 + 2] cycloaddition of isatins, 2-(aminomethyl)pyridine and isatin-based imines proceeded readily, and furnished novel imidazolidine-dispirooxindoles in up to 84% yield with up to >99:1 diastereoselectivity. The relative configuration of the imidazolidine-dispirooxindoles was firmly confirmed on the basis of X-ray single crystal structure analysis. The reaction mechanism was assumed to account for the diastereoselective formation of the imidazolidine-dispirooxindoles.

In this work, six novel axially unfixed biaryl-based water-compatible bifunctional organocatalysts were designed and synthesized for the organocatalytic access to a variety of 3-alkyl-3-hydroxy-2-oxindole derivatives via aldol reactions in water. Organocatalyzed by 5a, the direct aldol reactions of isatins with enolisable ketones underwent readily in water, furnishing the structurally diverse 3-alkyl-3-hydroxy-2-oxindoles in various stereoselectivities (up to>99% dr and >99% ee). Moreover, a plausible transition state of the conducted aldol reactions was hypothesized to shed light on the observed stereoselectivities of the obtained 3-alkyl-3-hydroxy-2-oxindoles.

A new family of axially unfixed biaryl-based water-compatible bifuctional organocatalysts were designed and synthesized for the asymmetric direct Michael reaction of cyclohexanone with various nitroolefins in water. One of the organocatalysts incorporates pyrrolidine and arylsulfonamide motifs as active organocatalytic sites, and axially unfixed biaryl as a skeleton; with this organocatalyst, the direct Michael reactions proceeded readily, furnishing the desired Michael adducts in high yields (up to 99% yield) with high levels of stereocontrol (up to >99:1 dr and 94% ee).

In this work, 2,2′-biphenol-based prolinamide water-compatible C 2- and C 1-symmetrical organocatalysts were synthesized with the use of enantiopure N-Cbz-(S)-proline as chiral source. Under the optimal reaction conditions, the C 1-symmetrical organocatalyst performed efficiently in the direct aldol reactions in water, thus delivering the desired aldol adducts in high yields (up to 100% yield) with excellent stereocontrol (up to 97:3 dr and 98% ee). The observed stereochemical outcome of the direct aldol reactions in water was interpreted by the proposed transition state.

We introduce a non-uniform gravity-like force field to control the granular flow state in a quasi-one-dimensional system, and study the system by the molecular dynamics simulation. We find that the granular flow under non-uniform force field can be well described by a density wave with fixed time period if a fixed particle number condition is used. The base frequency of the density wave does not depend on the position of the flow, while both the average density and oscillation amplitude of the flow vary continuously with the position. The formation of the density wave results from the aggregation of the granules in the decelerated region and the feed-back mechanism in the fixed particle number condition.

A series of chiral phenylpyridines possessing a fused chiral bridge were synthesized diastereoselectively via cascade cyclizations, where N-acyliminium ions including an enantiopure α-amino acid residue were involved. The absolute configuration of the synthesized phenylpyridines was identified unambiguously by using nuclear Overhauser effect difference and circular dichroism (CD) measurements on the basis of literature methods. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

A family of novel axially unfixed biaryl-based, water-compatible bifunctional organocatalysts were designed and synthesized for asymmetric catalytic direct aldol reactions in water. These organocatalysts are comprised of prolinamide, aromatic sulfonamide and biaryl motifs. Under the optimal reaction conditions, one organocatalyst in particular delivered excellent stereocontrol (up to 99% ee and 99:1 dr) in direct aldol reactions of cyclohexanone with a variety of aromatic aldehydes in water.

A series of novel axially chiral 2,2′-bipyridine N,N′-dioxides bearing C1 or C2-symmetry have been synthesized by the use of enantiopure α-amino acids as chiral sources. The absolute stereochemistry of the axial chirality of these organocatalysts has been clearly assigned by means of CD measurements together with literature protocols. The reactivities and enantioselectivities of these organocatalysts have been examined in the reactions of aromatic aldehydes with allyltrichlorosilane, thus providing the desired products with moderate yields and enantioselectivies.

Under mild reaction conditions, the tandem cycloadditions of cyclic N-sulfonylimines with in situ generated Huisgen 1,4-dipoles from dialkyl acetylenedicarboxylates and pyridines underwent readily, and delivered highly functionalized polycyclic 1,2,3,4-tetrahydropyrimidine-fused benzosultams in low to excellent chemical yields with excellent diastereoselectivities.

In the presence of 10 mol% of Na2CO3, the desired imidazolidine-spirooxindoles were obtained in 81–99% yield with up to 99 : 1 dr by means of the diastereoselective [3 + 2] cycloaddition of N-acylhydrazine-derived imines with 3-isothiocyanato oxindoles. Single-crystal X-ray structure analysis was conducted to determine the relative stereochemistry of the imidazolidine-spirooxindoles. Diastereoselective access to the imidazolidine-spirooxindoles was hypothesized by the proposed mechanism.