Synthesis and characterization of 1-(3,5-di-tert-butyl)pyrazolyldiphenylphosphine and its gold(I) complex

1-(3,5-Di-tert-butyl)pyrazolyldiphenylphosphine was prepared from 3,5-di-tert-butyl)pyrazole and chlorodiphenylphosphine. It reacted with (Me₂S)AuCl to afford a Au(I) complex bearing the pyrazolylphosphine ligand in a monodentate coordination mode.     

Eu(OTf)3-catalyzed oxidation of 5-alkylidene-4,5-dihydrofurans: A new approach to functionalized furylhydroperoxides

Here reported is an unusual catalytic ability of Eu(OTf)₃ in the oxidative conversion of 5-alkylidene-4,5-dihydrofuran derivatives in the corresponding furylhydroperoxides with tert-butyl hydroperoxide. Furthermore, an enantioselective process of disproportionation of furylhydroperoxides has been highlighted in the presence of the Jacobsen’s catalyst (S,S)-(+)-N,N′-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminomanganese(III) chloride.     

Aerial oxidation of substituted aromatic hydrocarbons catalyzed by Co/Mn/Br− in water-dioxane medium

Aerial oxidation of substituted aryl aromatic hydrocarbons were carried out using Co/Mn/Br⁻ catalyst system in water-dioxane medium in the range 14–56 bar air and temperature 383–423 K. The combination of optimum catalyst concentration of salts Co(OAc)₂, Mn(OAc)₂ and NaBr (1:3:10 molar ratio) in water-dioxane (1:2 mole ratio) is found catalyze aerial oxidation of substituted aryl aromatic to give corresponding oxygenated products. Under the optimized conditions, p-cymene gave p-isopropyl benzaldehyde (33.1%), p-isopropylbenzyl alcohol (54.7%) and p-isopropyl benzoic acid (3.3%), respectively, at p-cymene conversion 40.2%. Similarly, oxidation of p-methoxy toluene gave p-methoxy benzaldehyde (87.4%), benzyl alcohol (5.5%), and p-methoxy benzoic acid (6%), while oxidation of p-tert-butyl toluene yielded p-tert-butyl benzaldehyde (87%), p-tert-butyl benzyl alcohol (5.7%) and p-tert-butyl benzoic acid (6.1%), at conversions 16.4% and 36.1%, respectively. It is found that Co/Mn/Br⁻catalyst system in water-dioxane medium is effective in the aerial oxidation of substituted aromatic hydrocarbons to get corresponding alcohol and aldehydes in greater yields.     

One-pot microwave synthesis of tertiary phosphine sulfides directly from aromatic alkenes,elemental phosphorus and sulfur in KOH–DMSO system

Aromatic alkenes (vinylbenzene, 1-(tert-butyl)-4-vinylbenzene, 1-chloro-4-vinylbenzene) react with red phosphorus and elemental sulfur in the superbasic system KOH–DMSO(H₂O) under microwave irradiation (600 W, 6–8 min, Ar) in the presence of hydroquinone to afford tris(2-phenylethyl)-, tris[2-(4-^tBu-phenyl)ethyl]- and tris[2-(4-Cl-phenyl)ethyl]phosphine sulfides in 53%, 38% and 42% yield, respectively.     

Selective oxidation of indole by chloroperoxidase immobilized on the mesoporous molecular sieve SBA-15

The selective oxidation of hydrocarbons is an important value-enhancing chemical transformation in particular with respect to fine chemicals and pharmaceuticals production. Enzymatic oxidations operate under mild reaction conditions and produce little if any waste. However, its industrial use is still limited mainly due to their high cost and the low space time yields. In the present work, chloroperoxiase from Calariomyces fumago immobilized on the mesoporous molecular sieve SBA-15 was applied for the oxidation of indole to 2-oxoindole using hydrogen peroxide or tert.-butyl hydroperoxide as oxidants. The performance of the immobilized enzyme was found to be superior to native chloroperoxidase with respect to maximum conversion and pH range applicable. However, immobilized CPO is still sensitive to high concentrations of hydrogen peroxide. The use of tert.-buty hydroperoxide is found to avoid this problem, but the reaction rate is significantly reduced.     

固定化细胞催化合成6-氰基-(3R,5R)-二羟基己酸叔丁酯工艺研究

采用硅藻土作载体,聚乙烯亚胺和戊二醛作交联剂来固定化E.coli BL21(DE3)/pCDFDuet-gdh-cr共表达菌株,以此来催化6-氰基-(5R)-羟基-3-羰基己酸叔丁酯[(5R)-1]合成6-氰基-(3R,5R)-二羟基己酸叔丁酯[(3R,5R)-2],考察了硅藻土-聚乙烯亚胺-戊二醛固定化细胞的催化性能,进一步优化了固定化细胞催化合成(3R,5R)-2工艺。结果表明:在固定化细胞用量100g/L、葡萄糖与底物质量浓度比为1:1、转化温度30℃、pH7.0、流速12mL/min、100 g/L的(5R)-1转化完全的条件下,填充床式反应器可以连续反应五个批次,转化570 g/L的(5R)-1,较搅拌式反应器提高了107.3%,较游离细胞间歇催化操作提高了185%。     

具有非对映选择性还原6-氰基-（5R）-羟基-3-羰基己酸叔丁酯活性的微生物菌株筛选与鉴定

6-氰基-（3R,5R）-二羟基已酸叔丁酯是合成阿托伐他汀钙的关键手性前体。从自然环境中筛选得到-株具有非对映选择性还原6·氰基-（5R）-羟基-3-羰基已酸叔丁酯活性的茵株X25,结合表型特征、生理生化特征和分子遗传学鉴定,确定茵株X25属于季也蒙毕赤酵母（Pichiaguilliermondii）。研究了P．guilliermondliX25静息细胞非对映选择性还原6-氰基-（5R）-羟基-3-羰基己酸叔丁酯制备6-氰基-（3R,5R）-二羟基己酸叔丁酯过程。结果表明,最佳催化条件为35℃、pH值7．0;在低底物转化率时,能够制备光学纯6-氰基-（3R,5R）-二羟基己酸叔丁酯。     

Polymeric structures of a pair of linear,dicarboxylate (tpy)2Ru2+ analogues

The preparation and solid-state structures of homoleptic Ru(II) complexes based on the ligands 4′-(4-carboxyphenyl)tpy (L₁) (where tpy = 2,2′:6′,2″-terpyridine) and 4′-(4-carboxyphenyl)-4,4″-di-(tert-butyl)tpy (L₂) are described. Both complexes are found to possess polymeric solid-state structures due to hydrogen-bonding interactions. The first complex, [Ru(L₁)₂]²⁺, exhibits a more closely-packed structure relative to that of [Ru(L₂)₂]²⁺, which was found to have a porous solid-state structure due to the steric bulk of the tert-butyl groups.     

Electrosynthesis and structural characterization of a novel aryl ether trimer

The structure of a novel trimer formed by three p-tert-butyl anisole moieties via the controlled potential electrolysis of p-tert-butyl anisole was determined by X-ray diffraction method. By cyclic voltammetry, we report a multistep electron transfer, each followed by a chemical reaction, resulting in an ECECEC mechanism. Preparative scale oxidation of p-tert-butyl anisole in dry acetonitrile leads to its two first oligomers. The symmetrical dimer, 2,2′-dimethoxy-5,5′-di-tert-butylbiphenyl, shows that the favored coupling sites are those in the ortho position of the methoxy group. The title compound, namely the 1-methoxy-bis-2,3-(2′-methoxy-5′-tert-butylphenyl)-4-tert-butylbenzene crystallizes in triclinic space group P-1 with a = 10.571(3) Å, b = 11.739(1) Å, c = 12.733(2) Å, α = 74.64(1)°, β = 88.71(2)°, γ = 76.58(2)°, V = 1480.8(5) Å³, and Z = 2. The structural analysis reveals that two p-tert-butyl anisole moieties are linked in ortho position on a third p-tert-butyl anisole fragment.     

Synthesis and properties of polyacetylenes containing carbazolylmethyl groups

Novel acetylene monomers containing carbazolymethyl groups, 3,5-bis[(3,6-di-t-butyl)carbazolylmethyl]-1-ethynylbenzene (1), 3-(3,6-di-t-butyl)carbazolylmethyl-1-ethynylbenzene (2), and 4-(3,6-di-t-butyl)carbazolylmethyl-1-ethynylbenzene (3) were synthesized, and polymerized with [(nbd)RhCl]₂-Et₃N, Rh⁺(nbd)[η⁶-C₆H₅B⁻(C₆H₅)₃], and WCl₆-n-Bu₄Sn catalysts. The corresponding polyacetylenes with number-average molecular weights ranging from 1600 to 115,000 were obtained in 18%-quantitative yields. The UV-vis absorption band edge wavelengths of the polymers obtained with W catalyst were longer than those of the Rh-based polymers. The photoluminescence quantum yields of the W-based polymers were 1.1-3.1%, while those of the Rh-based ones were 0.18-4.1%.     

Friedel–Crafts green alkylation of xylenes with tert-butanol over mesoporous superacid UDCaT-5

Friedel–Crafts green alkylation of xylenes with tert-butanol was investigated in the presence of mesoporous superacidic catalysts named as UDCaT-4, UDCaT-5 and UDCaT-6. The catalysts are modified versions of zirconia showing high catalytic activity, stability and reusability. The catalytic activity is in the order: UDCaT-5 (most active) > UDCaT-6 > UDCaT-4 > sulfated zirconia (least active). Synergistic effect of very high sulfur content present (9% (w/w) S) and preservation of tetragonal phase in UDCaT-5, in comparison with sulfated zirconia (4% (w/w) S), were responsible for higher catalytic activity. The performance of UDCaT-5 in alkylation of xylenes was studied with tert-butanol with reference to selectivity and stability. Alkylation of m-xylene over UDCaT-5 gives 96% conversion of tert-butanol with 82% selectivity towards 5-tert-butyl-m-xylene (5-TBMX) under optimum reaction conditions. The formation of products is correlated with the acidity of the catalyst. The reactions were conducted in liquid phase at relatively low reaction temperatures (130–160 °C). A systematic investigation of the effects of various operating parameters was done to describe the reaction pathway. The reaction was carried out without any solvent in order to make the process cleaner and greener. An overall second order kinetic equation was used to fit the experimental data, under the assumption that both xylene and tert-butanol are weakly adsorbed. An independent study of dehydration of tert-butanol (TBA) was also done. Alkylation of o-xylene and p-xylene with tert-butanol was also studied. The overall process is green and clean.     

Multinuclear Cu(II) Schiff Base Complex as Efficient Catalyst for the Chemical Coupling of CO2 and Epoxides: Synthesis, X-ray Structural Characterization and Catalytic Activity

Abstract  

The synthesis, X-ray structure, spectroscopic and catalytic properties of sterically hindered Schiff-base ligands (L₁H = N-[allylamine]-3,5-di-tert-butyl salicylaldimine, L₂H=N-[2-amino-5-methyl pyridine]-3,5-di-tert-butyl salicylaldimine and L₃H=N-[2-amino-6-methyl pyridine]-3,5-di-tert-butyl salicylaldimine), and their mononuclear Cu(II) complex for L₁H with multinuclear Cu(II) complexes for L₂H and L₃H, were described. The copper(II) complexes of these ligands were synthesized by treating an methanolic solution of the appropriate ligand with an appropriate amount of CuCl₂·2H₂O. The ligands and their copper(II) complexes were characterized by FT-IR, UV–Vis, ¹H-NMR, elemental analysis, measurement of room temperature magnetic moment, and X-ray structural determination. The reaction of the L₂H and L₃H ligands in a 1:1 mol ratio with CuCl₂·2H₂O afforded ionic copper metal(II) complexes in the presence of NEt₃. The Cu(II) metal complexes tested as catalysts for the formation of cyclic organic carbonates from carbon dioxide and liquid epoxides which served as both reactant and solvent. [Cu₃(L₂)₄]Cl₂·CuCl₂ complex which has 5-methyl substituent on the pyridine ring showed high catalytic activity for chemical coupling carbon dioxide with epoxides (propylene oxide (PO), epichlorohydrine (EC) and 1,2-epoxy butane (EB)) selectively.     

Asymmetric Epoxidation of α,β-Unsaturated Ketones over Heterogenized Chiral Proline Diamide Complex Catalyst in the Solvent-Free Condition

Chiral copper proline diamide complex has been immobilized on surface of mesoporous silica. These heterogenized complex catalysts were examined as asymmetric catalysts for the epoxidation of α,β-unsaturated carbonyl compounds with hydrogen peroxide, tert-butyl hydroperoxide and urea hydroperoxide as the oxidants under solvent-free condition. Enantiomeric excesses of up to 84% can be achieved conveniently with a good conversion using these promising catalysts.     

Formation of triacylglycerol core aldehydes during rapid oxidation of corn and sunflower oils with tert-butyl hydroperoxide/Fe2+

The lipid ester core aldehydes formed during a rapid oxidation (7.8 M tert-butyl hydroperoxide, 90 min at 37°C) of the triacylglycerols of purified corn and sunflower oils were isolated as dinitrophenylhydrazones by preparative thin-layer chromatography and identified by reversed-phase high-performance liquid chromatography with on-line electrospray ionization mass spectrometry and by reference to standards. A total of 113 species of triacylglycerol core aldehydes were specifically identified, accounting for 32–53% of the 2,4-dinitrophenylhydrazine (DNPH)-reactive material of high molecular weight representing 25–33% of the total oxidation products. The major core aldehyde species (50–60% of total triacylglycerol core aldehydes) were the mono(9-oxo)nonanoyl- and mono(12-oxo)-9,10-epoxy dodecenoyl- or (12-oxo)-9-hydroxy-10,11-dodecenoyl-diacylglycerols. A significant proportion of the total (9-oxo)nonanoyl and epoxidized (12-oxo)-9,10-dodecenoyl core aldehydes was found in complex combinations with hydroperoxy or hydroxy fatty acyl groups (6–10% of total triacylglycerol core aldehydes). Identified were also di(9-oxo)nonanoylmonoacylglycerols (0.5% of total) and tri(9-oxo)nonanoylglycerols (trace). The identification of the oxoacylglycerols was consistent with the products anticipated from tert-butyl hydroperoxide oxidation of the major species of corn and sunflower oil triacylglycerols (mainly linoleoyl esters). However, the anticipated (13-oxo)-9,11-tridecadienoyl aldehyde-containing acylglycerols were absent because of further oxidation of the dienoic core aldehyde. A significant proportion of the unsaturated triacylglycerol core aldehydes contained tert-butyl groups linked to the unsaturated fatty chains via peroxide bridges (2–9%). The study demonstrates that rapid peroxidation with tert-butyl hydroperoxide consitutes an effective method for enriching natural oils and fats in triacylglycerol core aldehydes for biochemical and metabolic testing.     

Electrode reaction mechanisms for the reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide

The reduction of tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide has been investigated at platinum and glassy carbon electrodes in DMF. It is known from the studies of Maran et al. that peroxides reduction mechanisms generally involve at first a slow electron transfer concerted with the scission of the peroxide bond. Then the radical produced at the electrode is immediately reduced, which leads to a two electrons consumption. Similar results were obtained in this study for tert-butyl peracetate, lauryl peroxide and dibenzoyl peroxide. Besides, the determination of the number of electrons involved in the reduction at different time scales gave a number of two for lauryl peroxide, dibenzoyl peroxide, tert-butyl peroxybenzoate and di-tert-butyl peroxide and showed that this transfer is followed, in the case of tert-butyl peracetate, by a subsequent chemical reaction consuming a part of the substrate.     

Synthesis of new tripodal ligand: N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]benzylamine.: Catecholase activity of two series of tripodal ligands with some copper (II) salts

A synthesis of new tripodal ligand: N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]benzylamine is reported. Copper (II) complexes of compounds: N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)-amines (L1–L5) and N,N-bis[(1,5-dimethylpyrazol-3-yl)methyl]-amines (L6–L9) were examined for their catalytic activities. The dioxygen complexes of copper (II) were generated in situ by stirring copper salts and the tridentate pyrazole ligands. It has been found that the oxidation of 3,5-di-tert-butylcatechol is very efficient to give 3,5-di-tert-butylquinone. Ligand structure has proven critical in controlling not only the formation of complexes but also their subsequent reactivity. The nature of junction between the pyrazolic rings and the benzene have a large effect on the oxidation reaction rate.     

LSD1小分子抑制剂的合成及抗肿瘤活性研究

设计并合成了一系列以苯甲酰肼类结构为母核的赖氨酸特异性组蛋白去甲基化酶1(LSD1)小分子抑制剂,并研究其体外抗肿瘤活性。首先,通过体外酶水平单浓度抑制实验进行了初步评价,并随后进一步考察目标化合物对多种LSD1高表达肿瘤细胞株增殖的抑制作用,化合物结构经质谱及核磁共振表征确证。活性评价结果显示,3-(((3R,5S)-3,5-二甲基吗啉代)磺酰基)-N'-(7-羟基-2,3-二氢-1H-茚-1-亚基)苯甲酰肼、N'-(1-(5-氯-2-羟基苯基)亚乙基)-3-(((3R,5S)-3,5-二甲基吗啉代)磺酰基)苯甲酰肼和N'-(4-氯-7-羟基-2,3-二氢-1H-茚-1-亚基)-3-((4-吗啉代哌啶-1-基)磺酰基)苯甲酰肼可显著抑制肿瘤细胞的增殖,并有4个目标化合物对体外多种LSD1高表达的肿瘤细胞株增殖有抑制作用,其中3-(((3R,5S)-3,5-二甲基吗啉代)磺酰基)-N'-(7-羟基-2,3-二氢-1H-茚-1-亚基)苯甲酰肼对BGC823、HCT116、A2780s的半数抑制浓度分别为0.32、0.54、0.90μmol/L。     

Synthesis and bacteriostatic properties of acylarylureas and alkylarylureas

Fatty substituted ureas (RNHCONHR’) were prepared where R is an aliphatic acyl or alkyl group and R’ is a substituted phenyl group or a thiazole group. The benzene ring was generally substituted with chlorine, nitro, hydroxy, or a combination of these groups. The compounds were ineffective against gram-negative microorganisms but a number of samples inhibited the growth ofStaphylococcus aureus at 1 ppm. Bacteriostatic activity was generally observed where the acyl or alkyl group contained 6–10 carbon atoms and where R’ is 4-nitrophenyl, 4-chloro-3-nitrophenyl or a thiazole group derived from 2-amino-5-nitrothiazole. Scattered activity at 1 ppm was observed where R’ is 3-nitrophenyl, 2,4- and 3,5-dichlorophenyl, 2-hydroxy-5-chlorophenyl, 2-hydroxy-5-nitrophenyl, 3-nitro-4-hydroxyphenyl, 3,5-dinitrophenyl and 2-nitro-4-chlorophenyl. The alkylureas appear to be more active than the acylureas.     

Growth of silver nanoparticles on poly(acrylic acid) brushes and their properties

A simple procedure is employed for the growth of silver nanoparticles (Ag NPs) onto the silicon substrate modified by poly(acrylic acid) (PAA) brushes, via: (1) surface-initiated ATRP of tert-butyl acrylate on Si surface to the preparation of poly(tert-butyl acrylate) brushes, (2) acid hydrolysis of PBA to the formation of PAA, and (3) in situ synthesis of Ag NPs via chemical reduction of AgNO₃ in the presence of PAA brushes. The polymer brushes are thoroughly characterized. Moreover, Ag nanoparticles are homogeneously immobilized into the brush layer and have been used to fabricate a sensor platform of surface-enhance Raman scattering for the detection of organic molecules and effectively catalyze the reduction of methylene blue by NaBH₄.     

Synthesis of PAA-g-PNIPAM well-defined graft polymer by sequential RAFT and SET-LRP and its application in preparing size-controlled super-paramagnetic Fe3O4 nanoparticles as a stabilizer

A series of well-defined double hydrophilic graft copolymers, poly(acrylic acid)-g-poly(N-isopropylacrylamide) (PAA-g-PNIPAM), was employed as a novel water-soluble coating for constructing superparamagnetic iron oxide nanoparticles. The copolymer was synthesized via a three-step procedure: firstly, a well-defined hydrophobic PtBA-based backbone, poly(tert-butyl 2-((2-chloropropanoyloxy)-methyl)acrylate)-co-poly(tert-butyl acrylate), (PtBCPMA₁₉-co-PtBA₁₈), was prepared through RAFT copolymerization of a new trifunctional acrylic monomer, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate and tert-butyl acrylate; secondly, taking this backbone as a macroinitiator to initiate SET-LRP of N-isopropylacrylamide resulted in well-defined (poly(tert-butyl 2-((2-chloropropanoyloxy)methyl)-acrylate)-co-poly(tert-butyl acrylate))-g-poly(N-isopropylacrylamide) ((PtBCPMA-co-PtBA)-g-PNIPAM) amphiphilic graft copolymers with relatively narrow polydispersities (M_w/M_n ≤ 1.31); thirdly, handling (PtBCPMA-co-PtBA)-g-PNIPAM in acidic conditions afforded PAA-g-PNIPAM graft copolymers. The resulting PAA-g-PNIPAM copolymers were directly utilized as a polymeric stabilizer in the preparation of superparamagnetic Fe₃O₄ nanoparticles. The particle size can be readily tuned in the range of 12.1–23.2 nm by varying the amount of PAA-g-PNIPAM copolymer or the length of PNIPAM side chain. Besides, the structure and properties of prepared Fe₃O₄/polymer nanocomposites were characterized by XRD, FT-IR, TGA, TEM, and magnetic measurement in detail.