From solution-phase to solid-phase enyne metathesis: crossover in the relative performance of two commonly used ruthenium pre-catalysts

A crossover in the ability of two distinct ruthenium-based metathesis pre-catalysts to effect the synthesis of dialkenylboronic esters in solution and on the solid-phase was observed. Specifically, while the Grubbs 2nd generation pre-catalyst 3 affords a greater degree of conversion to product than the Hoveyda-Grubbs pre-catalyst 2 in a solution-phase enyne-metathesis reaction, this trend is reversed in the solid-phase variant. Systematic investigation showed this trend to be general, regardless of variations in the homoallylic alcohol and alkynylboronic ester components of the reaction, as well as in the type of solid support employed. Experiments to determine a mechanistic hypothesis for this trend highlighted the significance of the ruthenium remaining bound to the substrate after metathetic rearrangement and found the presence of phosphine ligand to be detrimental to the success of the solid-phase reaction. Therefore, these results suggest an expanded role for phosphine-free pre-catalysts, such as 2, in challenging solid-phase metathesis reactions.     

3,4-二氢-3-甲基-4-氧代咪唑[5,1-d]并[1,2,3,5]四嗪-8-甲酸苯磺酰基呋咱氮氧基酯的合成

以3,4-二氢-3-甲基-4-氧代咪唑[5,1-d]并[1,2,3,5]四嗪-8-甲酰胺和苯磺酰基呋咱氮氧化物为原料,通过肖滕-鲍曼法合成了5种新的咪唑四嗪衍生物——3,4-二氢-3-甲基-4-氧代咪唑[5,1-d]并[1,2,3,5]四嗪-8-甲酸苯磺酰基呋咱氮氧基酯,其结构经1H NMR,IR,MS和元素分析确证。     

Solid-phase synthesis of metal-complex containing peptides

We report the synthesis of Fmoc protected single amino acid chelates (SAAC) and their metal complexes. The modified amino acids are suitable for solid-phase peptide synthesis. The use of 4-hydroxymethylbenzoic acid AM (HMBA-AM) resin allows the nucleophilic cleavage of the peptide-metal complexes from the resin without decomplexation.     

富勒烯氢化物的合成研究进展

综述了十几年来富勒烯氢化物各种合成方法, 不同的氢化方法所得的氢化物不同; 并对富勒烯氢化物在储氢材料方面的应用作了展望.     

含聚硅氧烷链双马来酰亚胺的合成与表征

合成了Ｎ－（４－羟基苯基）马来酰亚胺和含聚硅氧烷链双马来酰亚胺，并用ＦＴＩＲ、１ＨＮＭＲ、元素分析、ＧＰＣ、ＤＴＡ和ＴＧ对其进行了表征。     

Phenol Solvothermal Synthesis of JBW-Type Zeolites

Phenol was used as an aromatic and acidic solvent in solvothermal synthesis.JBW-type zeolites were successfully synthesized in a phenolic system.The as-synthesized microporous crystals were characterized by powder X-ray diffraction analysis and scanning electron microscopy techniques.The results indicate that phenol is a good organic solvent and has a huge potential of application in studying crystallization mechanism and synthesizing novel microporous materials.     

Preparation of Nano-Sized γ-Al2O3 Supported Iron Catalyst for Fischer-Tropsch Synthesis by Solvated Metal Atom Impregnation Methods

Two types of small iron clusters supported on γ-Al2O3-RT(dehydroxylated at room temperature) and γ-Al2O3-800 (dehydroxylated at 800 ℃) were prepared by solvated metal atom impregnation (SMAI) techniques. The iron atom precursor complex, bis(toluene)iron(0) formed in the metal atom reactor, was impregnated into γ-Al2O3 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by TEM, M(o)ssbauer, and chemisorption measurements, and the results show that higher concentration of surface hydroxyl groups of γ-Al2O3-RT favors the formation of more positively charged supported iron cluster Fen/γ-Al2O3-RT, and the lower concentration of surface hydroxyl groups of γ-Al2O3-800 favors the formation of basically neutral supported iron cluster Fen/γ-Al2O3-800. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the rapid decomposition of precursor complex, bis(toluene)iron(0), and favors the formation of relatively large iron cluster. Consequently, these two types of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fen/γ-Al2O3-RT in F-T reaction is similar to that of the unreduced α-Fe2O3 and that of Fen/γ-Al2O3-800 is similar to that of the reduced α-Fe2O3.     

丙氨酰-谷氨酰胺的简便有效合成

谷氨酰胺 (Ｇｌｎ)是肠道必需氨基酸 ,是肠粘膜细胞氧化的重要燃料。肠粘膜缺乏Ｇｌｎ将严重损伤肠屏障功能 ,创伤性休克及化疗应激可加重损害 ,导致肠粘膜萎缩 ,肠道细菌移位 ,甚至促发脓毒症和多器官功能不全 (ＭＯＤＳ) [1] 。但Ｇｌｎ性质不稳定 ,不能耐高温消毒 ,因此 ,一般氨基酸制剂不含Ｇｌｎ。Ａｌａ Ｇｌｎ为Ｇｌｎ代谢前体 ,溶解度高 ,性质较Ｇｌｎ稳定 ,能耐受热灭菌 ,在体内数分钟即分解出Ｇｌｎ ,能部分补偿肠道所需Ｇｌｎ ,减少严重创伤及腹腔注射化疗药物 5 氟尿嘧啶 (5 ＦＵ)引发的小肠粘膜形态功能改变 ,细菌移位 ,降低…     

Phosphomimetic sulfonamide and sulfonamidoxy analogues of (Lyso)phosphatidic acid

Lysophosphatidic acid (LPA) and phosphatidic acid (PA) are potent bioactive lipid mediators of signal transduction and are inactivated by phosphatases. To obtain receptor-isoform selective ligands with neutral phosphomimetic head groups, we performed the stereoselective synthesis of LPA and PA analogues with trifluoromethanesulfonamide and trifluoromethanesulfonamidoxy moieties replacing the phosphomonoester.     

褪黑激素的合成与表征

以吲哚为起始原料,经4步反应合成了褪黑激素(MLT) 吲哚(1)在甲醇中羟基化得到5-羟基吲哚(2),(2)同2-氯乙胺在乙酸乙酯中进行胺乙基化反应得到5-羟基色胺(3),(3)与硫酸二甲酯在甲苯中对羟基进行醚化,得到5-甲氧基色胺(4),(4)经乙酰化得到产物MLT,收率80%