An Efficient Synthesis of 5,6‐Dimethoxy 1‐ and 2‐Naphthols via Teuber Reaction

Based on the oxidation of 1,5‐naphthalenediol ( 4 ) and 6‐bromo‐2‐naphthol ( 9 ) via Teuber reaction, an efficient synthesis of 5,6‐dimethoxy‐1‐naphthol ( 1 ) and 5,6‐dimethoxy‐2‐naphthol ( 2 ) was achieved with high overall yield (16% for 1 and 25% for 2 ). The key steps of the synthetic strategy involved the oxidation of naphthols ( 4 and 9 ) to the corresponding naphthoquinones ( 5 and 10 ) and the conversion of 5,6‐dimethoxy‐2‐naphthaldehyde to 5,6‐dimethoxy‐2‐naphthol formate through Baeyer‐Villiger oxidation‐rearrangement.     

Reaction of Ketene Dithioacetals with Pyrazolylcarbohydrazide： Synthesis and Biological Activities of Ethyl 5-Amino-1-（5＇-methyl-1 ＇-t-butyl-4＇-pyrazolyl）carbonyl-3-methylthio-1 H-pyrazole-4-carboxylate

The title compound, C16H23N5O3S, ethyl 5-amino-1-(5‘-methyl-1‘-t-butyl-4‘-pyrazolyl)carbonyl-3-methylthio-1H-pyrazole-4-carboxylate (5) has been synthesized by the treatment of ethyl 2-cyano-3,3-dimethylthioacrylate with 1-t-butyl-5-methyl-4-hydrazinocarbonylpyrazole (4) in refluxed ethanol. The possible mechanism of the above reaction was also discussed. The results of biological test show that the title compound has fungicidal and plant growth regulation activities.     

Separation of flavonoids from Millettia griffithii with high‐performance counter‐current chromatography guided by anti‐inflammatory activity

Millettia griffithii is a unique Chinese plant located in the southern part of Yunnan Province. Up to now, there is no report about its phytochemical or related bioactivity research. In our previous study, the n‐hexane crude extract of Millettia griffithii revealed significant anti‐inflammatory activity at 100 μg/mL, inspiring us to explore the anti‐inflammatory constituents. Four fractions (I, II, III, and A) were fractionated from n‐hexane crude extract by high‐performance counter‐current chromatography with solvent system composed of n‐hexane/ethyl acetate/methanol/water (8:9:8:9, v/v) and then were investigated for the potent anti‐inflammatory activity. Fraction A, with the most potent inhibitory activity was further separated to give another four fractions (IV, V, VI, and B) with solvent system composed of n‐hexane/ethyl acetate/methanol/water (8:4:8:4, v/v). Compound V and fraction B exhibited remarkable anti‐inflammatory activity with nitric oxide inhibitory rate of 80 and 65%, which was worth further fractionation. Then, three fractions (VII, VIII, and IX) were separated from fraction B with a solvent system composed of n‐hexane/ethyl acetate/methanol/water (8:1:8:1, v/v), with compound VIII demonstrating the most potent inhibitory activity (80%). Finally, the IC₅₀ values of compound V and VIII were tested as 38.2 and 14.9 μM. The structures were identified by electrospray ionization mass spectrometry and¹H and ¹³C NMR spectroscopy.     

BF3‐Oet2/Et3SiH‐Mediated Rearrangement of 4‐Aryl‐5,5‐Diphenylazapan‐4‐Ols

Synthesis of 2‐(2‐arylethyl)‐3,3‐diphenylpyrrolidines has been established starting from different 4‐aryl‐5,5‐diphenylazepan‐4‐ols via boron trifluoride etherate/triethylsilane‐mediated rearrangement.     

Synthesis of Novel Chiral Biphenylamine Ligand 6,6'‐Dimethoxy‐2,2′‐diaminobiphenyl

A new chiral ligand 6,6′‐dimethoxy‐2,2′‐diaminobiphenyl was successfully prepared from 3‐nitrophenol via iodination, Ullmann coupling, and reduction. The resolving reagent (2R, 3R)‐ or (2S,3S)‐2,3‐di (phenylaminocarbonyl)tartaric acid was prepared from commercially available tartaric acid in large scale and was used to resolve the racemic 6,6′‐dimethoxy‐2,2′‐diaminobiphenyl. The chiral 6,6′‐ dimethoxy‐2,2′‐diaminobiphenyl obtained was proved to be enantiomerically pure.     

Carbon‐13 NMR and PM3 Study on the Substituent Effect of 1‐Aryl‐3,3‐Difluoro‐2‐Halocyclopropenes

The substituent‐induced chemical shifts (SCS) of C2 and C3 on the ¹³C NMR spectra of 1‐aryl‐3,3‐difluoro‐2‐halocyclopropenes were studied. The correlation between SCS and Hammett constants shows that the tendency of effect by the substituents on the phenyl ring is BrC2(ρ = 4.66) > ClC2(ρ = 4.50) and ClC3(ρ = ?1.63) > BrC3(ρ = ?1.41). The DSP treatment further confirms the SCS of C2 and C3 are the main contribution of the resonance effect and field effect, respectively. Those results of the incremental shifts reveals that the gem‐difluorocyclopropenyl bearing the phenyl group possesses a triple bond character, which is also observed in IR spectra with high n?_C=C (1768–1945 cm^?1).     

Characterization of regenerated starch from 1‐ethyl‐3‐methylimidazolium acetate ionic liquid with different anti‐solvents

A comparison study of the structures and properties of starches regenerated from 1‐ethyl‐3‐methylimidazolium acetate ([Emim][OAc]) using different anti‐solvents (water, ethanol, or both water and ethanol) was conducted. The starch regenerated with water presented a V‐type crystalline structure whereas the one regenerated in ethanol displayed amorphous structure. Moreover, when an ethanol–water–ethanol method was used for regeneration, the product showed a weak V‐type crystalline structure. SAXS and FTIR were also used to investigate the molecular order of native and regenerated starches. With water used for regeneration, the aggregation and rearrangement of starch molecules occurred more easily. The increased enzyme resistance and thermal stability of regenerated starch with water could be ascribed to the rearrangement of molecular chains forming an aggregated structure with some degree of order. The reconstitution of starch molecules during regeneration with different anti‐solvents changed the multiscale structures and properties of the starch. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1231–1238     

Synthesis and properties of new organo‐soluble and strictly alternating aromatic poly(ester‐imide)s from 3,3‐bis[4‐(trimellitimidophenoxy)phenyl]phthalide and bisphenols

A series of new strictly alternating aromatic poly(ester‐imide)s having inherent viscosities of 0.20–0.98 dL/g was synthesized by the diphenylchlorophosphate (DPCP) activated direct polycondensation of the preformed imide ring‐containing diacid, 3,3‐bis[4‐(trimellitimidophenoxy)phenyl]phthalide (I), with various bisphenols in a medium consisting of pyridine and lithium chloride. The diimide–diacid I was prepared from the condensation of 3,3‐bis[4‐(4‐aminophenoxy)phenyl]phthalide and trimellitic anhydride. Most of the resulting polymers showed an amorphous nature and were readily soluble in a variety of organic solvents such as N‐methyl‐2‐pyrrolidone (NMP) and N,N‐dimethylacetamide (DMAc). Transparent and flexible films of these polymers could be cast from their DMAc solutions. The cast films had tensile strengths ranging 66–105 MPa, elongations at break from 7–10%, and initial moduli from 1.9–2.4 GPa. The glass‐transition temperatures of these polymers were recorded between 208–275 °C. All polymers showed no significant weight loss below 400 °C in the air or in nitrogen, and the decomposition temperatures at 10% weight loss all occurred above 460 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1090–1099, 2000     

Syntheses and properties of organosoluble polyamides and polyimides based on the diamine 3,3‐bis[4‐(4‐aminophenoxy)‐3‐methylphenyl]phthalide derived from o‐cresolphthalein

Diamine 3,3‐bis[4‐(4‐aminophenoxy)‐3‐methylphenyl]phthalide (BAMP) was derived from the o‐cresolphthalein, and then it was polycondensated with various aromatic dicarboxylic acids and dianhydrides to synthesize polyamides (PAs) and polyimides (PIs), respectively. PAs have inherent viscosities of 0.78–2.24 dL/g. Most of the PAs are readily soluble in a variety of solvents such as DMF, DMAc, and NMP and afforded transparent and tough films from DMAc solutions. The cast films have tensile strengths of 75–113 MPa as well as initial moduli of 1.71–2.97 GPa. These PAs have glass transition temperatures (T_gs) in the range of 242–325°C, 10% weight loss temperatures occur up to 473°C, and char yields are between 57 and 64% at 800°C in nitrogen. PIs were first synthesized to form polyamic acids (PAAs) by a two‐stage procedure that included a ring‐opening reaction, followed by thermal or chemical conversion to polyimides. Inherent viscosities of PAAs are between 0.71 and 1.63 dL/g. Most of the PIs obtained through the chemical cyclodehydration procedure are soluble in NMP, o‐chlorophenol, m‐cresol, etc., and they have inherent viscosities of 0.58–1.32 dL/g. T_gs of these PIs are in the range of 270–305°C and show 10% weight loss temperatures up to 477°C. PIs obtained through the thermal cyclodehydration procedure have tensile strengths of 72–142 MPa, elongations at break of 8–19%, and initial moduli of 1.80–2.72 GPa. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 455–464, 1999     

Facile Synthesis of Substituted Ethyl 2‐(Chloromethyl)‐2‐hydroxy‐2H‐1‐benzopyran‐3‐carboxylates

Ethyl 2‐(chloromethyl)‐2‐hydroxy‐2H‐chromene‐3‐carboxylates 2a – 2j have been synthesized by reaction of substituted salicylaldehydes with ethyl 4‐chloro‐3‐oxobutanoate, in the presence of piperidine in CH₂Cl₂ at room temperature, in good yields.     

Formation and Molecular Structure of an Ion Pair Iron (II) Compound Derived from 2,6‐Bis‐ [1‐(2,6‐dibromophenylimino) ‐ethyl] pyridine and 2‐Acetyl‐6‐[1‐(2, 6‐dibromophenylimino)‐ethyl] pyridine

Two novel tridentate ligands of 2,6‐bis‐[l‐(2,6‐dibromophenylimino) ethyl] pyridine (L₁) and2‐acetyl‐6‐[1‐(2,6‐dibromophenylimino) ethyl] pyridine (L2) have been synthesized. The iron(II) complex of L₁ and L₂ has been characterized with the crystal structure of [Fe(L₁)(L₂)]²⁺ [FeCl₄]² CH₂Cl₂ [monoclinic, P2₁ (#11), a = 1.0562(4), b = 2.0928(4), c = 1.2914(2) nm, β = 100.12°, V = 2.810(1) nm³ D_c = 1.879 g/cm³ and Z = 2].     

Efficient and Green Synthesis of N‐aryl Pyrroles Catalyzed by Ionic Liquid [H‐NMP][HSO4] in Water at Room Temperature

A suitable and efficient method for the synthesis of N‐aryl pyrroles by using 2,5‐dimethoxy tetrahydrofuran and several primary aromatic amines in the presence of the catalytic amount of [H‐NMP][HSO₄] under room temperature was described. This method has the advantages such as; easy reaction workup, absolutely separated of catalyst from the reaction mixture and smoothly recyclability of catalyst. In this reaction, N‐substituted pyrroles were obtained as desired products in excellent yields and short reaction times via green and one‐pot procedure.     

Application of 10‐ethyl‐acridine‐3‐sulfonyl chloride for HPLC determination of aliphatic amines in environmental water using fluorescence and APCI‐MS

A simple, sensitive method for the determination of aliphatic amines based on a sulfonylation reaction using 10‐ethyl‐acridine‐3‐sulfonyl chloride (EASC) as pre‐column labeling reagent with fluorescence detection and APCI‐MS identification has been developed. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by HPLC with an excitation maximum at λ_ex 270 nm and an emission maximum at λ_em 430 nm. Identification of derivatives was carried out by online post‐column MS in positive‐ion mode. Comparing with the widely used 5‐dimethylaminonaphthalene‐1‐sulfonylchloride (Dansyl‐Cl), EASC‐amine derivatives not only exhibited high fluorescence but also exhibited excellent MS ionizable potential. Detection limits obtained from 0.10 pmol injection, at a S/N of 3, were 4.0–12.7 fmol. The mean intra‐ and inter‐assay precision for all aliphatic amine levels were <3.84 and 3.21%, respectively. Excellent linear responses were observed with coefficients of >0.9995.     

Unexpected Course of the Reaction of 2‐Unsubstituted 1H‐Imidazole 3‐Oxides with Ethyl Acrylate

The attempted ethenylation at C(2) of 2‐unsubstituted 1H‐imidazole N‐oxides with ethyl acrylate (=prop‐2‐enoate) in the presence of Pd(OAc)₂ does not occur. In contrast to the other aromatic N‐oxides, the [2+3] cycloaddition of imidazole N‐oxides predominates, and 3‐hydroxyacrylates, isomeric with the cycloadducts, are key products for the subsequent reaction. The final products were identified as dehydrated 2+1 adducts of 1H‐imidazole N‐oxide and ethyl acrylate. The role of the catalyst is limited to the dehydration of the intermediate 3‐hydroxypropanoates to give 1H‐imidazol‐2‐yl‐substituted acrylates.     

Polymorph of Dibenzo‐24‐Crown‐8 and its Mercury Complex

Dibenzo‐24‐crown‐8 is studied herein as a flexible ligand able to adopt different conformations, as well as for the complexation of mercury. The recrystallization of dibenzo‐24‐crown‐8 (DB24C8) from dry THF gives a new polymorphic structure of this ligand. This new structure is described and compared to the literature compound. Additionally, coordination of this ligand to mercury iodide HgI₂ is studied.     

A Geomimetic Approach to the Formation and Identification of Fossil Sterane Biomarkers in Crude Oil: 18‐nor‐D‐homo‐Androstane and 5α,14β‐Androstane

A diazonium ion derived from 18‐aminoandrostane rearranged upon decomposition by a carbonium and a carbenium ion to furnish a mixture of a cyclopropanated compound and two D ‐homo‐androstenes. Hydrogenation of this mixture gave the saturated hydrocarbons, 18‐nor‐D ‐homo‐androstane and 5α,14β‐androstane, which are both fossil sterane biomarkers in Neoproterozoic crude oil. The so far unknown constitution and configuration as well as the geochemical genesis were established by this experiment. The starting material for this investigation, 18‐aminoandrostane, was prepared in twelve steps from androstan‐17‐one (12.5 % overall yield) with a Barton reaction as the key step.     

Copper‐catalyzed homo‐ and cross‐coupling reactions of terminal alkynes in ethyl lactate

The bio‐based chemical ethyl lactate (EL) has been discovered to be an excellent medium for the Glaser‐type homo‐ and cross‐coupling reactions of terminal alkynes. Good to excellent yields of conjugate diynes have been obtained under ligand‐free and mild heating conditions in the presence of CuI and molecular oxygen. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of 3,3‐Disubstituted Oxindoles via a Three‐Component Condensation Reaction in H2O

An efficient method has been developed for the synthesis of a novel series of unsymmetrically 3,3‐disubstituted oxindoles in good‐to‐high yields by a one‐pot three‐component condensation reaction of 2‐hydroxynaphthalene‐1,4‐dione, an isatin, and a barbituric acid derivative, in H₂O, and with p‐toluenesulfonic acid as a catalyst, at 90°. The effects of solvent, temperature, and the amount of catalyst on the yield of the reaction have been investigated. Additionally, the influence of hydrophilicity and hydrophobicity of the reactants on the selectivity of products has been examined.     

Synthesis and characterization of thermally stable sulfonated polybenzimidazoles obtained from 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone

A novel sulfonated aromatic diacid, 3,3′‐disulfonyl‐4,4′‐dicarboxyldiphenylsulfone (DSDCDPS), was successfully synthesized from 4,4′‐dimethyldiphenylsulfone by sulfonation and further oxidation. A series of sulfonated polybenzimidazoles (sPBI‐SS) with various sulfonation degrees was prepared from DSDCDPS, 4,4′‐sulfonyldibenzoic acid and 3,3′‐diaminobenzidine by solution copolycondensation in poly(phosphoric acid). The chemical structure of the resulting sPBI‐SS was confirmed by FTIR and ¹H NMR. The DSDCDPS‐based sPBI‐SS with the number‐average molecular weights of 32,000–55,000 were easy to dissolve in polar aprotic solvents such as DMF, DMSO, and DMAc, and could be cast into transparent, tough, and flexible membranes. The membranes presented good thermal stabilities (5% weight loss temperatures higher than 430 °C), and the thermal degradation activation energies of the sulfonic group of sPBI‐SS40 evaluated under N₂ by both Ozawa and Kissinger methods were 266.06 and 264.79 kJ/mol, respectively. The membranes also exhibited high storage moduli, glass transition temperatures (above 238 °C) and tensile strengths (～80 MPa), in addition to water uptakes (22.3–25.2%) and low swelling degrees (<14.0%). © 2005 Wiley Periodicals, Inc. J Polym Sci A: Polym Chem 43: 4363–4372, 2005     

One‐Pot Organocatalytic Enantioselective Michael/Povarov Domino Strategy for the Construction of Spirooctahydroacridine‐3,3′‐oxindole Scaffolds

An asymmetric organocatalytic one‐pot strategy for the construction of spirooctahydroacridine‐3,3′‐oxindole scaffolds has been successfully developed by means of a domino Michael/Povarov reaction sequence. The one‐pot protocol affords the chiral spirocyclohexaneoxindoles bearing an octahydroacridine motif with five stereocenters in good to high yields (up to 89 % yield) with excellent to perfect diastereoselectivities (up to >20:1 d.r.) and enantioselectivities (up to >99 % ee). This highly efficient one‐pot domino procedure will allow diversity‐oriented syntheses of this intriguing class of compounds with potential biological activities.