Photoinduced Decarboxylative Amino-Fluoroalkylation of Maleic Anhydride

A photoinduced decarboxylative three-component coupling reaction involving amine, maleic anhydride, and fluorinated alkyl iodides has been developed, leading to synthetically valuable fluoroalkyl-containing acrylamides with a high E selectivity. A broad array of substrates including monoprotected amino acid are capable coupling partners. Preliminary mechanistic studies suggest a stepwise process. This reaction represents the first example of photoinduced decarboxylative difunctionalization of maleic anhydride.     

芳环取代的俘精酸酐的合成及光致变色反应研究

本文报道四个芳环取代的俘精酸酐:2-亚异丙基-3-[1-(4-甲氧苯基)-亚乙基]-丁二酸酐(BF1); 2-亚异丁基-3-[1-(4-甲氧苯基)-亚乙基]-丁二酸酐(BF2);2-亚异丙基-3-[1-(α-萘基)-亚乙基]-丁二酸酐(NF1); 2-亚异丙基-3-[1-(β-萘基)-亚乙基]-丁二酸酐(NF2)的合成及其光致变色性质。测定了它们在不同溶剂中光致变色前后的吸收光谱。利用纳秒级激光闪光光解技术研究了它们的光致变色过程, 并讨论了其光致变色机理。结果表明, 这类芳环取代的俘精酸酐的光致环合反应是经过激发单重态进行的快速过程。     

丁二酸酐与SnCl2·2H2O共催化含水乳酸缩聚制备高分子量聚乳酸

用丁二酸酐与SnCl2.2H2O共催化含水乳酸本体缩聚,合成黏均分子量为6×104的聚乳酸.合成反应时间短,聚乳酸产率高、纯度好.单体为含水10%～15%的乳酸.聚合方法环境友好,不使用任何共沸溶剂.讨论了催化剂用量、反应温度、聚合时间等对聚合反应的影响,并用红外光谱和核磁共振光谱对合成的聚乳酸进行了表征.     

A mild and efficient catalytic alkylative monofunctionalization of cyclic anhydrides.

Substituted succinic and glutaric anhydrides undergo a nickel-catalyzed monofunctionalization with organozinc reagents as nucleophiles. The reaction proceeds readily with a variety of substrates, employs commercially available or readily attainable reagents, tolerates sensitive functionality on both partners, and affords the product ketoacids in moderate to high yields. The use of a chiral phosphinooxazoline results in a desymmetrization of a meso anhydride to provide the ketoacid in 85% yield and 79% ee.     

Kinetics of esterification of succinic anhydride with methanol by homogeneous catalysis

Kinetic data on the esterification of succinic anhydride with methanol catalyzed by sulfuric acid have been obtained using a stirred batch reactor. In addition to get a precise ascertainment of the parameters the esterification of monomethyl succinate with methanol has been studied separately. Several experiments have been carried out with different initial molar ratios and different amounts of sulfuric acid at various temperatures. The conversion to dimethyl succinate at 30–65°C follows a first-order rate expression with respect to each component. A theoretical rate equation is derived by the following reaction mechanism: (1) succinic anhydride is protonated by sulfuric acid to form a reaction intermediate, (2) irreversible esterification to monomethyl succinate, (3) protonation of the monoester, and (4) the esterification to dimethyl succinate proceeds reversibly. The resultant kinetic equation fitted the experimental data quite well and is given by the expression: © 1994 John Wiley & Sons, Inc. © 1994 John Wiley & Sons, Inc.     

New elastomeric networks based on functionalized ethylene–propylene rubbers and hydroxyl terminated polybutadiene. I. A kinetic study on the monoesterification

Ethylene–propylene random copolymers bearing grafted succinic anhydride functions have been reacted with an α,ω-hydroxyl telechelic polybutadiene to obtain elastomeric interpolymer complexes. A kinetic study has been carried out by infrared techniques to study the influence of the addition of catalyst, stoichiometry, and temperature on the degree of monoesterification reaction.     

Computational study on kinetics and mechanisms of unimolecular decomposition of succinic acid and its anhydride

The mechanisms and kinetics of unimolecular decomposition of succinic acid and its anhydride have been studied at the G2M(CC2) and microcanonical RRKM levels of theory. It was shown that the ZsgsZ conformer of succinic acid, with the Z-acid form and the gauche conformation around the central C-C bond, is its most stable conformer, whereas the lowest energy conformer with the E-acid form, ECGsZ, is only 3.1 kcal/mol higher in energy than the ZsgsZ. Three primary decomposition channels of succinic acid producing H2O + succinic anhydride with a barrier of 51.0 kcal/mol, H2O + OCC2H3COOH with a barrier of 75.7 kcal/mol and CO2 + C2H5COOH with a barrier of 71.9 kcal/mol were predicted. The dehydration process starting from the ECGCZ-conformer is found to be dominant, whereas the decarboxylation reaction starting from the ZsgsZ-conformer is only slightly less favorable. It was shown that the decomposition of succinic anhydride occurs via a concerted fragmentation mechanism (with a 69.6 kcal/mol barrier), leading to formation of CO + CO2 + C2H4 products. On the basis of the calculated potential energy surfaces of these reactions, the rate constants for unimolecular decomposition of succinic acid and its anhydride were predicted. In addition, the predicted rate constants for the unimolecular decomposition of C2H5COOH by decarboxylation (giving C2H6 + CO2) and dehydration (giving H3CCHCO + H2O) are in good agreement with available experimental data.     

马来酸酐接枝聚丙烯的等温结晶动力学研究

用ＤＳＣ法追踪了马来酸酐接枝聚丙烯的等温结晶过程，讨论了马来酸酐降低聚丙烯球晶径向生长自由能，提高结晶速率，但降低聚丙烯结晶度的物理和化学机制．同时探讨了马来酸酐的接枝对球晶生长和成核机制的影响．     

PREPARATION OF STARCH SUCCINATE WITH INTERMEDIATE DS BY AQUEOUS SLURRY REACTION

The succinylation of cornstarch by slurry reaction has been studied using sodium hydroxide as catalyst.Several reaction parameters affecting the succinylation were investigated including the concentration of starch in water,the ratio of succinic anhydride to starch,the reaction time and the reaction temperature,The favorable conditions for an intermediate degree of substitution(DS) and reasonably high reaction efficiency(RE) are pH 8.5-9.0,50% starch by weight to water.succinic anhydride to starch 1/1(w/w),reaction time 4h,reaction temperature 30℃ .Under these conditions,the DS of 0.45 and RE of 28% were achieved.The addition of an adequate amount of crosslinking agent imparted starch succinate water absorbency.     

RuCl3/PPh3催化顺酐加氢为琥珀酸酐的反应机理研究

利用原位^31P NMR,IR技术跟踪了RuCl3/PPh3催化顺酐加氢过程，并考察了酸碱的添加对反应的影响。根据实验结果，提出了在RuCl3/PPh3催化剂体系作用下，顺酐均相加氢生成琥珀酐的反应历程：RuCl3/PPh3在反应体系中生成活性物种RuHCl(PPh3)，顺酐以C＝C双键与Ru-H活性物种配位生成配合物，此配合物分子内氢转移，形成金属烷基化物，该化合物再与氢进行氧化加成，还原脱出产物琥珀酸酐和Ru-H活性物种，完成整个催化循环。     

A novel one-pot isocyanide-based four-component reaction: synthesis of highly functionalized 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates

A new protocol has been developed for the efficient synthesis of structurally diverse 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates via a four-component reaction of hydrazine hydrate, dialkyl acetylenedicarboxylates, isocyanides and various cyclic anhydrides such as succinic anhydride, maleic anhydride and phthalic anhydride in ethanol/acetone (1:1) at room temperature in good to moderate yields.     

Trifluoroacetic anhydride-mediated solid-phase version of the Robinson-Gabriel synthesis of oxazoles

A traceless solid-phase synthesis of oxazoles 4 via Robinson-Gabriel reaction of solid-supported alpha-acylamino ketones 2 has been achieved. The reaction requires that the cyclization precursor be linked to a benzhydrylic-type linker (compounds 2) and that trifluoroacetic anhydride be used as the cyclodehydrating agent. The solvent has a dramatic effect on the latter reaction, which goes to completion and follows a cyclative-type mechanism only when an ethereal solvent is used. Different synthetic routes have been investigated toward assembling compounds 2. The most straightforward one, which we have validated more extensively, comprises the reaction of Merrifield alpha-methoxyphenyl (MAMP) resin with an alpha-amino ketone to form compounds 1, which are, in turn, acylated. Other methodologies and strategies allowing for the synthesis of compounds 1 that have been investigated include direct alkylation of Rink amide resin; reductive amination of the latter with alpha-keto aldehydes; reaction of MAMP resin with alpha-amino alcohols, followed by oxidation; and protection of Rink amide resin with either 2,4-dinitrosulfonyl or allyl group, followed by alkylation and removal of protecting group. In addition, we disclose a novel variant of the Ugi four-component reaction that allows for the preparation of compounds 2 in a single synthetic step.     

Contemporaneous dual catalysis: chemoselective cross-coupling of catalytic vanadium-allenoate and π-allylpalladium intermediates

This paper presents a detailed investigation of a dual catalytic system that combines a vanadium-catalyzed Meyer-Schuster rearrangement and a palladium-catalyzed allylic alkylation. The implementation of this novel reaction relies on matching the formation rates of vanadium-allenoate and π-allylpalladium intermediates with their bimolecular coupling rate in order to minimize the undesired protonation or O-alkylation of the catalytically generated intermediates. Chemoselectivity in this dual catalytic process was successfully achieved by adjusting ligand structure and catalyst loading ratios of the vanadium and palladium catalysts. A great range of coupling partners for both the propargyl alcohol and allyl carbonate components are readily accommodated in this new transformation, which in turn provides a novel avenue to a variety of α-allylated α,β-unsaturated ketones, esters, and amides in moderate to excellent isolated yields.     

Multifunctional coupling agents. Part 4: Block copolymers based on amino terminated polyamide-12 and carboxy terminated poly(butylene terephthalate)

A carboxy terminated poly(butylene terephthalate) (PBT) was obtained by quantitative reaction of a hydroxy terminated PBT with succinic anhydride. Subsequent melt mixing with an amino group terminated PA12 did not result in the formation of linking groups between the components. Instead, the formation of succinimide terminal groups on the polyamide-12 (PA12) chains was observed.The same conversion in presence of a bifunctional coupling agent possessing one oxazoline and one oxazinone group yielded PA12/PBT block copolymers in high extent. DSC and microscopic measurements showed that a phase separated morphology is predominant.     

Comparison of the acylation of chitosan with succinic anhydride in aqueous suspension and in solution

Russian Chemical Bulletin - A homogeneous reaction in 1% AcOH and a heterogeneous reaction in aqueous suspension were used to obtain N-succinylchitosan from chitosan and succinic anhydride. The 1H...     

Free-radical-induced polymerization of epoxides in the presence of maleic anhydride

The free-radical-induced reactions of cyclohexene oxide in the presence of maleic anhydride have been found to lead to polyether in presence of AIBN and to a mixture of polyether, ester, and maleic anhydride adduct of polyether with di-tert-butyl peroxide (DTBP), the amounts of the mixture components depending on the concentration of DTBP and the temperature. Analogous reactions in the presence of succinic anhydride lead to no polyether. The obtained polyether has no hydroxyl group. The reaction appears to consist of three different steps, radical initiation, cationic propagation, and radical termination.     

Grafting of maleic anhydride to n-eicosane

Maleic anhydride was grafted to the linear hydrocarbon, n-eicosane, at 165°C in the presence of the free radical initiator, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne. The anhydride has a low solubility in eicosane and a multiple addition procedure was adopted. Grafted product which separated from the reaction mixture was fractionated and analyzed. The fractions contained on average 2–5.5 anhydride units/eicosane residue. ¹H- and ¹³C-NMR studies show that the grafts consist of single succinic anhydride rings. At the concentrations of maleic anhydride chosen for homogeneous reaction ( < 0.02 M) and at 165°C, poly(maleic anhydride) is above its ceiling temperature, so that succinic anhydride radicals cannot add maleic anhydride to form polymer side chains. Instead, these radicals abstract hydrogen atoms to yield grafts consisting of single anhydride units.     

丁二酸脱水制备丁二酸酐的微观反应机理研究

丁二酸脱水法是工业生产丁二酸酐的方法之一. 用量子化学密度泛函理论(DFT)对该反应的微观机理进行了详细研究, 得到了该反应的微观过程. 根据计算和分析可知: 丁二酸脱水制备丁二酸酐的微观反应途径为IM1→TS1→IM2→TS2→IM3→TS3→P＋H₂O, 在反应过程中IM3为氢键复合物, 整个反应的速控步为IM3→TS3→P＋H₂O, 其所需活化能为167.17 kJ/mol.     

Practical asymmetric synthesis of a non-peptidic alphavbeta3 antagonist

The development of a practical and highly convergent synthesis of an alpha(v)beta3 antagonist is described. The two key fragments present in this compound, a tetrahydropyrido[2,3-b]azepine ring system and a chiral 3-aryl-5-oxopentanoic acid, were constructed independently and then coupled at a late stage using a Wittig reaction. The pyridoazepine moiety was prepared from N-Boc 6-chloro-2-aminopyridine via directed ortho-metalation/alkylation followed by in situ cyclization. A Suzuki reaction was then used to attach the propionaldehyde side-chain required for Wittig coupling. The coupling partner was prepared from asymmetric methanolysis of a 3-substituted glutaric anhydride followed by elaboration of the acid moiety to the requisite beta-keto phosphorane. Using this route, kilogram quantities of the desired drug candidate were prepared.     

氟苯尼考琥珀酸单酯的合成工艺优化

以氟苯尼考和琥珀酸酐为原料,4-二甲氨基吡啶(DMAP)催化合成了氟苯尼考琥珀酸单酯。通过正交试验确定最佳反应条件为:氟苯尼考14 mmol,n(氟苯尼考)∶n(琥珀酸酐)=1.0∶1.5,w(DMAP)=4%,于60℃反应4 h,产率88.1%。在最佳反应条件下做放大实验,氟苯尼考3 kg,产率88.9%