Enantioselective recognition of chiral acids by supramolecular interactions with chiral AIEgens.

Novel chiral AIEgens bearing optically pure amino groups were synthesized and showed excellent discrimination for a series of chiral acidic compounds and amino acids. Interestingly, after supramolecular assembly with 4-sulfocalix[4]arene, the obtained complexes showed enhanced enantioselectivity for chiral acids.

Iron-Catalyzed Cycloaddition of Amides and 2,3-Diaryl-2-azirines To Access Oxazoles via C-N Bond Cleavage.

A novel and efficient iron-catalyzed cycloaddition reaction using readily available 2,3-diaryl-2-azirines and primary amides is reported. A wide range of trisubstituted oxazoles could be achieved in good yields with good functional group compatibility. In this transformation, two C-N bonds were cleaed and new C-N and C-O bonds were formed.

Crystal and Band-Gap Engineering of One-Dimensional Antimony/Bismuth-Based Organic-Inorganic Hybrids.

Hybrid halide perovskites are emerging semiconducting materials with a diverse set of remarkable optoelectronic properties. Besides the widely studied lead halide perovskites, Pb-free metal halides such as Bi- and Sb-containing hybrid organic-inorganic materials have shown potential as semiconductors and have been deemed candidates for optoelectronic devices. Here, we report a series of 1D Sb/Bi-based organic-inorganic hybrid alloys: [4ApyH]SbBiIBr, where 4ApyH stands for the 4-aminopyridine cations.

Tracking the dimensional conversion process of semiconducting lead bromide perovskites by mass spectroscopy, powder X-ray diffraction, microcalorimetry and crystallography.

The structural information of a material in both the solid state and solution state is essential to the in-depth understanding of the properties of inorganic-organic hybrid materials. A one-dimensional (1D) lead bromide formulated as [H][NH(CH)SS(CH)NH][HO][PbBr] (1) could be converted into a new two-dimensional (2D) complex, [NH(CH)SS(CH)NH][PbBr] (2), by soaking the crystals in water. The isolated 2D compound showed single-layer lead-halide perovskite structures.

Monodisperse Bismuth-Halide Double Perovskite Nanocrystals Confined in Mesoporous Silica Templates.

Metal halide perovskites have fascinating electronic properties and have already been implemented in various devices. Although the behavior of the properties of lead halide perovskite nanocrystals has been studied, the properties of lead-free perovskite nanocrystals are less well-understood because synthesizing them is still very challenging. Here, a simple and popularizable method has been demonstrated to grow monodisperse bismuth-halide double perovskite nanocrystals, CsAgBiBr (1), inside three kinds of mesoporous silica templates.

Brønsted-Acid-Catalyzed Synthesis of 3-Alkoxy and 3-Sulfamido Indanones via a Tandem Cyclization.

Brønsted-acid-catalyzed allylic substitution reactions of the in situ generated 3-hydroxy indanones with alcohols and sulfamides were investigated, which provided a facile route for the synthesis of a large variety of 3-alkoxy and 3-sulfamido indanones. The key intermediates, 3-hydroxy indanones, were obtained through the intramolecular Meyer-Schuster rearrangement of o-propargyl alcohol benzaldehydes. The resulting 3-benzyloxy indanone could be selectively modified by allylic sulfonamidation and reduction reactions.

KI-catalyzed oxidative cyclization of α-keto acids and 2-hydrazinopyridines: efficient one-pot synthesis of 1,2,4-triazolo[4,3-]pyridines.

A one-pot approach to substituted 1,2,4-triazolo[4,3-]pyridines has been developed that is based on a KI-catalyzed oxidative cyclization of α-keto acids and 2-hydrazinopyridines. This transition-metal-free procedure was highly efficient and shows good economical and environmental advantages.

KSO/TEMPO-Induced Cascade Oxidative Cyclization/1,2-Migration of Electron-Deficient Groups: Strategy for the Construction of 1 H-Pyrrol-2(3 H)-ones.

A KSO/TEMPO-induced oxidative cyclization of N-unprotected enaminoesters and enaminones that gave 1 H-pyrrol-2(3 H)-ones in good yields with broad functional group compatibility is reported. This method provides easy access to 1,2-carbon migration of ester or acyl group under transition-metal-free conditions.

Modular 2,3-diaryl-2H-azirine synthesis from ketoxime acetates via CsCO-mediated cyclization.

A modular 2H-azirine synthesis from ketoxime acetates via Cs2CO3-mediated cyclization has been developed. The reaction utilizes easily available starting materials and provides a general synthetic route to 2,3-diaryl-2H-azirines in good to excellent yields under mild conditions, which is complementary to the conventional approaches for the synthesis of 2H-azirines. A gram-scale reaction was performed to demonstrate the scale-up applicability of this synthetic method.

Iron-Catalyzed Radical Cycloaddition of 2H-Azirines and Enamides for the Synthesis of Pyrroles.

A novel and efficient Fe-catalyzed radical cycloaddition of 2H-azirines and enamides for the synthesis of substituted pyrroles has been developed. The radical cycloaddition reaction proceeded through a conceptually new Fe(II)-catalyzed homolytic cleavage of C-N bond of 2H-azirines sequential radical cyclization with enamides. The reaction used readily available starting materials, tolerated various functional groups, and afforded valuable triaryl-substituted pyrroles in good to high yields under mild reaction conditions.

Synthesis of Polycarbonyl Pyrroles via KSO-Mediated Oxidative Cyclization of Enamines.

A novel KSO-promoted oxidative cyclization of enamines is described. A variety of enamines having diverse functional groups and substitution patterns react well using KSO as the oxidant in the absence of catalyst. This protocol provides a very simple route for the synthesis of polycarbonyl pyrroles and has the advantages of readily available starting materials, mild reaction conditions, and a wide scope of substrates.

Regioselective Intermolecular [2 + 2]-Cycloaddition of α-Iodo-Unsaturated Ketones Promoted by Diisobutylaluminum Hydride.

The development of intermolecular [2 + 2]-cycloaddition of α-iodo-unsaturated ketones in the presence of diisobutylaluminum hydride (Dibal-H) is reported to produce various trispirocyclic derivatives containing a cyclobutane ring. This sequential lactonization/[2 + 2]-cycloaddition proceeds in high regioselectivity under mild conditions.

Recent developments in the group-1B-metal-catalyzed synthesis of pyrroles.

Pyrroles are important synthetic targets as a result of their occurrence in numerous biologically active molecules, their important roles in diverse living processes, and their utility as versatile intermediates. As a consequence, numerous efforts focused on the development of concise and efficient methods for the construction of pyrroles. Compared with other transition metals, the group 1B metals (Cu, Ag and Au) are probably more versatile and widely used for the synthesis of pyrroles in organic chemistry.

N'-(5-Bromo-2-hy-droxy-benzyl-idene)-4-methyl-benzohydrazide.

The mol-ecule of the title compound, C(15)H(13)BrN(2)O(2), displays an E conformation with respect to the C=N double bond and the dihedral angle between the planes of the benzene rings is 3.1 (2)°. An intra-molecular O-H⋯N inter-action generates an S(6) ring.

3-Hydr-oxy-N'-(5-hydr-oxy-2-nitro-benzyl-idene)-2-naphthohydrazide.

The mol-ecule of the title compound, C(18)H(13)N(3)O(5), displays an E configuration with respect to the C=N double bond. The dihedral angle between the benzene ring and the naphthyl system is 1.1 (2)°.

N'-(5-Hydr-oxy-2-nitro-benzyl-idene)-2-methoxy-benzohydrazide.

The asymmetric unit of the title compound, C(15)H(13)N(3)O(5), contains two independent mol-ecules. Each mol-ecule displays an E configuration with respect to its C=N double bond. The dihedral angles between the two benzene rings are 11.

(E)-4-Chloro-N'-[1-(4-hydroxy-phenyl)-ethylidene]benzohydrazide.

The mol-ecule of the title compound, C(15)H(13)ClN(2)O(2), displays a trans configuration with respect to the C=N double bond. The dihedral angle between the two benzene rings is 15.1 (3)°.

(E)-4-Chloro-N'-(4-hydroxy-benzyl-idene)-benzohydrazide.

The mol-ecule of the title compound, C(14)H(11)ClN(2)O(2), displays a trans configuration with respect to the C=N double bond. The dihedral angle between the two benzene rings is 12.8 (3)°.

4-Chloro-N'-(2-hydr-oxy-1-naphthyl-idene)benzohydrazide.

The mol-ecule of the title compound, C(18)H(13)ClN(2)O(2), displays a trans configuration with respect to the C=N double bond. The dihedral angle between the benzene and naphthyl ring systems is 6.0 (2)°.

4-Chloro-N'-(5-chloro-2-hydroxy-benzyl-idene)benzohydrazide.

The mol-ecule of the title compound, C(14)H(10)Cl(2)N(2)O(2), displays a trans configuration with respect to the C=N double bond and has an intramolecular O-H⋯N hydrogen bond. The dihedral angle between the two benzene rings is 1.4 (2)°.

[Determination of fraxinellone in root bark of Dictamnus dasycarpus by RP-HPLC].

Objective: To develop a RP-HPLC method for determination of fraxinellone in Dictamnus dasycarpus.

Method: RP-HPLC conditions were as follows: AT-LICHROM C18(4.6 mm x 250 mm) column, MeOH-H2O (70:30) as a mobile phase, detection wavelength 240 nm, column temperature 25 degrees C, Flow velocity 0.