通过轴向配位反应实现4-乙烯基吡啶聚合物的卟啉功能化

通过轴向配位反应,将四苯基卟啉锌(ZnTPP)键合在4-乙烯基吡啶(4VP)与苯乙烯(St)共聚物P(4VP-co-St)的侧链,制得了卟啉功能化的大分子ZnTPP-P(4VP-co-St).通过FTIR与1H-NMR对其化学结构进行了表征,重点研究了时间、温度对轴配过程的影响,以及大分子轴配化合物ZnTPP-P(4VP-co-St)的谱学性能,对其光物理行为进行了较为深入的分析.研究结果表明,以共聚物P(4VP-co-St)的吡啶侧基为配体,通过轴向配位反应可顺利地制备卟啉功能化的大分子ZnTPP-P(4VP-co-St),且温度越低,键合量越大.该大分子具有类似于ZnTPP的特征电子吸收光谱与荧光发射光谱,同时也显示出轴向配位的特征.与小分子ZnTPP相比,ZnTPP-P(4VP-co-St)的吸收光谱和发射光谱都发生了明显的红移.大分子轴配化合物ZnTPP-P(4VP-co-St)的光物理行为也呈现出一定程度的高分子效应,随着大分子链中ZnTPP键合量的增大,相近的ZnTPP侧链单元之间会发生能量转移,使荧光发射强度有所减弱.     

Flüssig-Flüssig-Extraktion von Vanadium mit ausgewählten zweizähnigen Chelatbildnern

Liquid-Liquid Extraction of Vanadium with Bidentate Ligands The extraction of vanadium(V) as well as vanadium(IV) with thenoyltrifluoracetone, 1-phenyl-3-methyl-4-benzoylpyrazol-5-one, N-benzoyl-N-phenylhydroxylamine, maltol, di-2-ethylhexylphosphoric acid, and selected 8-quinolinols was studied in comparison with corresponding thioanalogue compounds. In the reaction of vanadium(IV) with 7-methyl-8-quinolinol vanadium(IV) and vanadium(V) compounds were isolated side by side.     

Highly efficient solid-phase oxidative cleavage of olefins by OsO4-NalO4 in the intramolecular N-acyliminium Pictet-Spengler reaction

[reaction: see text] In the present investigation, solid-supported peptide olefins were converted quantitatively to aldehydes via the OsO(4)-NaIO(4)-mediated oxidative cleavage reaction. Addition of DABCO was essential to efficiently suppress the formation of hydroxymethyl ketone side products. The generated aldehydes were used in intramolecular N-acyliminium Pictet-Spengler reactions to produce highly pure pyrroloisoquinoline derivatives. The methodology was extended to allylglycine derivatives to enable the incorporation of pyrroloisoquinoline scaffolds within peptides.     

An improved protocol for the RuO4-catalyzed dihydroxylation of olefins

[reaction: see text] Dihydroxylation under ruthenium catalysis provides an easy access to syn-diols, although overoxidation is a common side reaction. Furthermore, the high catalyst loadings offset the lower price of ruthenium compared to osmium. In this paper, we present an improved protocol for the RuO(4)-catalyzed syn-dihydroxylation using only 0.5 mol % catalyst under acidic conditions. A variety of olefins can be hydroxylated in good to excellent yields with only minor formation of side products.     

Synthesis and Study of an N,N‐Disubstituted 4‐[(4‐Aminophenyl)diazenyl]benzaldehyde

An N,N‐disubstituted 4‐[(4‐aminophenyl)diazenyl]benzaldehyde (‘azo dye') with nematic phase was synthesized by reaction of the phenylpiperazine derivative with the formylbenzenediazonium salt. The salt was prepared by a simplified reaction of poly(aminobenzaldehyde) with NaNO₂ in the presence of HBF₄. The azo dye was further studied by crystallography. On the basis of molecular stacking identified from crystallography, the molecular modeling was carried out to explore the molecular interactions, and it was found that the attraction of two coplanar molecules with side‐to‐side contact is favored, and a nematic phase is thus formed during the thermal process.     

Preparation and radical ring-opening polymerization of 2-substituted-4-methylene-1,3-dioxolanes

2-Methyl-2-phenyl-4-methylene-1,3-dioxolane ( IIa ), 2-ethyl-2-phenyl-4-methylene-1,3-dioxolane ( IIb ), 2-phenyl-2-(n-propyl)-4-methylene-1,3-dioxolane ( IIc ), 2-phenyl-2-(i-propyl)-4-methylene-1,3-dioxolane ( IId ), 2-(n-heptyl)-2-phenyl-4-methylene-1,3-dioxolane ( IIe ), 2-methyl-2-(2-naphthyl)-4-methylene-1,3-dioxolane ( IIf ), and 2,2-diphenyl-4-methylene-1,3-dioxolane ( IIg ) were prepared and polymerized in the presence of a radical initiator. IIa–IIf were found to undergo vinyl polymerization with ring-opening reaction accompanying the elimination of ketone groups in bulk. IIg was found to undergo the quantitative ring-opening reaction accompanying the elimination of benzophenone in solution to obtain polyketone without any side reaction.     

Re-cyclization of 3-(E)-methyl 3-(4-oxo-4H-chromen-3-yl)acrylate with amines and their potential mechanism

The synthesis of 2-pyridone derivatives from different substituted amines and various 3-(E)-methyl 3-(4-oxo-4H-chromen-3-yl)acrylate derivatives was proposed and described. The optimized reaction conditions and the generality of the reaction were investigated, respectively. Moreover, less side products could be formed than the traditional method. Finally, based on the fact that (E)-methyl 2-(7-methoxy-4-oxo-3-((phenylamino)methylene)chroman-2-yl)acetate was separated and determined via X-ray single crystal diffraction, we could propose an interesting and reasonable reaction mechanism for the first time. The reaction could render this method particularly attractive for the efficient preparation of biologically and medicinally interesting molecules.     

Mesomorphic behaviour of 4-benzoyloxybenzoic acid and its binary mixture with 4-acetoxybenzoic acid

The nematic liquid crystalline property of 4-benzoyloxybenzoic acid (BBA) was observed by polarizing microscopy and X-ray diffraction. The structure of the hydrogen-bonded BBA dimer was verified by FT-IR, and the axial ratio ( l / d ) of the rod-like molecule was calculated to be 5.8, which is large enough to exhibit a liquid crystalline phase. The mesophase was stable at 240 C. At higher temperatures, for example, 270 C, the trans -esterification side reaction occurred. The binary phase diagram of BBA and 4-acetoxybenzoic acid shows the eutectic temperature at 175 C.     

Diastereoselective [4 + 4]-photocycloaddition reactions of pyran-2-ones: rapid access to functionalized 5-8-5 skeletons

Fused bicyclic pyran-2-ones with pendant furan side chains and an oxygenated stereogenic center adjacent to the pyranone ring oxygen were prepared via FeCl(3)-catalyzed Michael addition. Irradiation furnished the corresponding lactone-bridged tricyclic [4 + 4]-cycloadducts with good facial selectivity. Surprisingly, the major isomer resulted from approach of the furan from the same face as the protected alcohol. [reaction: see text]     

4 + 2]-annulations of chiral organosilanes: Application to the total synthesis of leucascandrolide A

Complete details of an asymmetric synthesis of leucascandrolide A (1) are described. The synthesis highlights the use of two diastereoselective [4 + 2]-annulations for the assembly of the functionalized bispyranyl macrolide 3. An efficient assembly and union of the oxazole-containing side chain 4 with macrolide 3 was carried out using a Mitsunobu reaction. A convergent route to the oxazole side chain was developed using a Sonogashira cross-coupling between 2-trifloyloxazole 16 and alkyne 17, which allowed for the installation of the C9'-C10' (Z)-olefin.     

Liquid Crystalline Side Chain Polysiloxanes with 4-Cyano- and 4-Alkoxy-Stilbene Mesogenic Units

Abstract

Side chain homo- and copolysiloxanes with 4-cyano- and 4-alkoxy-4′-stilbene mesogens, spaced apart from the backbone by oligomethylene segments of variable lengths, were synthesized via a hydrosilylation coupling reaction of five stilbene-containing α-olefins with four commercial poly(methylhydrosiloxane)s and poly(methyl-hydro-∞-dimethylsiloxane)s. Broad smectic phases were observed for the polysiloxanes with cyanostilbene mesogens, whereas the homologous with alkoxy-terminated stilbenes displayed only narrow mesophases in the high temperature range. Preliminary room tem-perature X-ray diffraction studies on mechanically oriented samples evidenced the occurrence of side chain crystallization, microphase separation and indicated the interdigitated smectic A nature of the mesophases.     

Synthesis of 4-Alkyl-4-alkoxybutenolides Having Unsaturated Side Chains via Chromium Carbene Complex Photochemistry: (+)-Cerulenin

The photochemical reaction between optically active ene carbamates and chromium alkoxycarbene complexes containing unsaturated aliphatic side chains was further developed. Although remote olefinic groups, including conjugated dienes, were tolerated, a homoallylic side chain underwent intramolecular reaction to give a strained cyclobutanone. (+)-Cerulenin was synthesized utilizing the photochemical reaction of an alkynylcarbene complex with an optically active ene carbamate and the bis(pi-crotyl)nickel halide alkylation of a vinyl bromide as key steps.     

由4',4''-二羟基-2-甲酸－三苯基甲烷及其衍生物制备高碳超支化芳香聚酯

合成了一系列含羟基和乙酰氧基的超支化聚酯,将4',4'二羟基-2-甲酸－三 苯基甲烷（酚酞啉）直接缩聚和将4~＇,4~＂-二羟基-2-甲酸－三苯基甲烷进行酯 交换反应都成功得到了超支化聚酯,以PS作标准物,由GPC测得的重均分子量为 2000到8000,~13C NMR测试表明聚合物支化度略高于50%,聚酯的玻璃化转变温度 依赖于末端和侧基官能团类型,该超支化聚酯末端含有反应性官能团,具有类似线 性高分子的高的热稳定性,相比之下,由于其大分子的形状和官能团的影响,末端 为乙酰氧基的超支化聚枉费显示了优良的溶解性能,这与一般线性高分子大不相同 ,由于氢键的存在,末端为羟基的超支化聚酯的溶解性能不佳,但是酸酯显示了 优良的溶解性能,这与一般线性高分子大不相同,由于氢键的存在,末端为羟基的 超支化聚枉费的溶解性能不佳,但是酸化可破坏氢键网络,得到的超支化聚酯可深 于一般有机溶剂。     

Stereoselective total synthesis of atpenins a4 and b, harzianopyridone, and NBRI23477 B

The stereoselective total synthesis of atpenins A4 (2) and B (3), harzianopyridone (4), and NBRI23477 B (5) have been developed using a convergent approach involving the coupling reaction of a common iodopyridine with an aldehyde corresponding to the appropriate side chain of the desired compound. Furthermore, the absolute configurations of atpenin B (3), harzianopyridone (4), and NBRI23477 B (5) have been unambiguously determined.     

Surface reactions of 4-aminothiophenol with heterobifunctional crosslinkers bearing both succinimidyl ester and maleimide for biomolecular immobilization

Surface reactions of 4-aminothiophenol (4-ATP) with a series of heterogeneous crosslinkers containing both maleimide and succinimidyl ester groups were investigated with infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Two types of surface reactions exist: (1) for most crosslinkers, a dominant reaction of amine and succinimidyl ester gave homogeneous maleimide-pendant surfaces; (2) for other crosslinkers, a side reaction between amine and maleimide, accompanying the main reaction, yielded heterogeneous surfaces with two linking groups, maleimide and succinimidyl ester. A typical example for the second case is the reaction of surface amines with N-succinimidyl-6-maleimidylhexanoate (SMH). Finally, a peptide, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH (GRGDSPC), was immobilized on the SMH-derived surface as a bridging structure through two linkages, cysteine thioether and glycine amide.     

Herstellung von substituierten 2-Aminooxazol-4-carbonitrilen

Preparation of Substituted 2-Aminooxazole-4-carbonitriles During our synthetic programme to convert 4-isoxazolylthioureas 3 into the corresponding carbodiimides 5 , a side reaction leading to the hitherto unknown 2-aminooxazole-4-carbonitriles 6 was observed. By selecting appropriate reaction conditions, it was possible to improve the yields of the carbodiimides 5 as well as of the novel oxazole-carbonitriles 6 at will, thus allowing the synthesis of 6 to be conducted in very good yields. To overcome the difficulty of isolating unstable carbodiimides, the synthesis of 6 is best carried out in a one-pot procedure. A limited mechanistic study showed that the formation of 6 proceeds via 5 as the only intermediate. The stability of the N?C?N bonds against base attack (depending strongly on both sterical hindrance and electronic-density factors) forms the only limitation of this new synthetic pathway to oxazole-4-carbonitriles.     

InBr3-catalyzed glycosidation of glycals with arylamines: an alternative approach to access 4-aminocyclopent-2-enones

To turn side products into major products, a novel strategy to access biologically active 4-aminocyclopent-2-enones was developed. These compounds were originally identified as side products but became major products when 3,5-dimethylpyran-3,4-diol 7a was used as the substrate and 30% InBr(3) as the catalyst. Aryl- or heteroarylamines as well as variously substituted glycals can be used in this reaction, and the corresponding 4-aminocyclopent-2-enones were obtained in moderate to good yields. These compounds can be further used to prepare 4-aminocarbocyclic nucleosides.     

4-(4-β-D-吡喃阿洛糖苷-苯基)-2-芳基-5-氰基-6-甲氧基吡啶的合成及镇静活性研究

以豆腐果苷为原料,与4-取代苯乙酮发生Schmidt-Claisen反应,得到一系列查儿酮结构的E-4-β-D-吡喃阿洛糖苷-苯乙烯基-4-取代苯乙酮衍生物3a-3h,其中3c、3e、3f为新化合物。 3a-3h在甲醇钠存在下,与1,3－丙二氰发生1,4-Michael加成,经关环、重排、氧化,得到4-(4-β-D-吡喃阿洛糖苷-苯基)-2-芳基-5-氰基-6-甲氧基吡啶系列豆腐果苷衍生物10a-10h,联氨催化还原10e而得到10i。共获得十二个未见文献报道的新化合物,其结构经1H NMR、IR和HRMS确证,并进行了药理活性筛选,结果表明,部分化合物具有比母体化合物更好的镇静催眠活性。同时,本文对Schmidt-Claisen反应存在的主要副反应进行了分析;对查儿酮与1,3－丙二氰在甲醇钠存在下反应生成吡啶衍生物反应机理进行了推导,提出了氧化脱氢形成吡啶的新机理。     

A novel synthesis of linear high-molecular-weight poly(4-vinylphenol) and poly[styrene-co-(4-vinylphenol)]

A novel synthesis of linear high-molecular-weight poly(4-vinylphenol) (PVPh) and poly[styrene-co-(4-vinylphenol)] (STVPh, 2 ) via demethylation reaction is developed. The parent polymers, poly(4-methoxystyrene) and poly[styrene-co-(4-methoxystyrene)] produced by free-radical polymerization, are converted to PVPh and STVPh ( 2 ), respectively, by being treated with trimethylsilyl iodide (TMSI) at room temperature. Both ¹H NMR and ¹³C NMR data show that methoxy is completely cleaved and converted to hydroxy after hydrolysis without crosslinking and other side reactions. In addition, size-exclusion chromatography data show that no chain scission occurs during group conversion.     

Practical Preparation of 3-Chloro-4-Methoxybenzylamine Hydrochloride

The title compound was prepared in a practical manner by chlorinating 4-methoxybenzylamine with sulfuryl chloride in acetic acid in 79–82% yields with little side reaction.