Highly Diastereoselective Synthesis of Polycyclic Indolines through Formal [4+2] Propargylic Cycloaddition of Indoles with Ethynyl Benzoxazinanones

A formal [4+2] propargylic annulation of indoles and pyrrole with ethynyl benzoxazinanones was described. This protocol provides a concise synthesis of tetrahydro‐5H‐indolo[2,3‐b]quinolines and tetrahydro‐3H‐pyrrolo[3,2‐b]quinoline, the core structures of alkaloid frameworks, featuring excellent yields, high diastereoselectivity, mild conditions and wide substrate scope.     

Overview of the Synthesis and Structure of Calix[n]quinones (n=4, 6, 8)

Calix[n]quinones, a class of cyclic oligomers composed of p‐benzoquinone structures connected by methylene, have multi‐conjugated carbonyl structures and adjustable cavities, which make their synthesis extremely attractive. In this minireview, synthetic methods of calix[n]quinones and recent synthetic experience of our group are summarized. The merits and demerits of various synthetic methods are briefly reviewed as well. When synthesizing calix[n]quinone (n≥6) with a larger ring, the reduction‐oxidation method is considered to be the most recommended.     

高容量锂离子电池正极复合材料pillar[5]quinone/CMK-3的制备

以有机醌类化合物柱[5]醌(pillar[5]quinone,P5Q)作为锂离子电池的正极材料,探索了其储锂性能。实验结果表明,P5Q首圈放电容量达到了431 mAh·g^-1,显示出100%的活性位点利用率。然而,P5Q在电解液中的溶解会导致循环过程中容量的衰减。采用超声法将P5Q填入有序介孔碳CMK-3的孔道,制备了P5Q/CMK-3复合材料,以此减少P5Q与电解液的接触,从而减缓了P5Q的溶解速率,提高了电池的循环稳定性。P5Q/CMK-3复合材料100次充放电循环后容量为300 mAh·g^-1,保持率高达71%,说明了该优化方法效果显著,提高了P5Q在锂离子电池中的实际应用价值。     

2-Methoxyhydroquinone from Vanillin for Aqueous Redox-Flow Batteries

We show the synthesis of a redox-active quinone, 2-methoxy-1,4-hydroquinone (MHQ), from a bio-based feedstock and its suitability as electrolyte in aqueous redox flow batteries. We identified semiquinone intermediates at insufficiently low pH and quinoid radicals as responsible for decomposition of MHQ under electrochemical conditions. Both can be avoided and/or stabilized, respectively, using H₃PO₄ electrolyte, allowing for reversible cycling in a redox flow battery for hundreds of cycles.     

SYNTHESES AND SOME PROPERTIES OF SULFOXIDES,SULFILIMINES, AMINOSULFONIUM SALTS AND SULFOXIMINES CONTAINING PYRIDINE NUCLEI

Abstract

Several 2-pyridyl sulfides (1) (e.g., methyl (1a), ethyl (1b), isopropyl (1c), benzyl (1d), 1-phenylethyl (1e), l-menthyl (If) 2-pyridyl sulfides; and bis(2-pyridylthio)methane (1g), and methyl 2-(N-oxy-pyridyl) sulfide (1h) were prepared by the usual method. Sulfoxides (2) were prepared by oxidation of the corresponding sulfides with m-chloroperbenzoic acid in good yields. A few sulfoxides were found to work as phase-transfer catalysts for some typical nucleophilic reactions in nonpolar solvents such as benzene, and in two-phase systems such as benzene-water. S-2-Pyridyl-N-(p-toluenesulfonyl) sulfilimines (3) were prepared upon treatment of sulfides with Chloramine-T. Hydrolysis of N-(p-toluenesulfonyl)-2-pyridyl-o-tolylsulfilimine (3i) with conc. sulfuric acid gave the corresponding free sulfilimine in a moderate yield. S-2-Pyridyl sulfoximines (4) were not obtained by the general method from the sulfoxides and hydrazoic acid. Alkyl-2-pyridyl sulfoximines, however, were obtained by oxidation of the free sulfilimines derived from the corresponding aminosulfonium salts (5) prepared by reaction of the sulfides with mesitylene-sulfonylhydroxylamine (MSH). These free sulfilimines and sulfoximines thus prepared were found to give adducts with a few copper salts.     

依赖PQQ的甲醇脱氢酶与甘氨酸作用后的进程曲线

从革蓝氏阴性甲基营养菌Ｎｏ．２细胞提取的甲醇脱氢酶（ＭＤＨ）是一种氧化还原酶，已证明其辅基是新辅基ＰＱＱ（吡咯喹啉醌），笔者在研究ＭＤＨ及其辅基的理化性质过程中，发现甘氨酸（ｇｌｙ）对ＭＤＨ影响极为特殊，随后，以此为出发点得到的试验数据，对解释目前国...     

Diels–Alder reaction of anthracene on grafted polysiloxane and cylindrical carbosilane dendrimer

Anthracene‐grafted polysiloxane was prepared by the dehydrocoupling between linear siloxane polymers and anthracenecarbinol. The cylindrical type of dendritic polysiloxane was prepared up to the second generation by the hydrosilation between polysiloxane and vinyltrichlorosilane, and the continual addition of allyl alcohol. The anthracene groups on cylindrical dendrimers were prepared by the reaction of Si? Cl bonds on the polymer and anthracenecarbinol. The Diels–Alder reaction of anthracene moieties on polysiloxane and maleimide derivatives, maleic acid anhydride, and 1,4‐quinone derivatives was carried out under mild conditions. The polymers prepared were characterized by NMR and gel‐permeation chromatography. Copyright © 2005 John Wiley & Sons, Ltd.     

Anionic [4+2] cycloaddition strategy in the regiospecific synthesis of carbazoles: formal synthesis of ellipticine and murrayaquinone A

Anionic [4+2] cycloaddition of furoindolones (e.g., 7 and 10) has been developed as an effective means to the synthesis of carbazoles. This reaction has been shown to be feasible with a wide variety of Michael acceptors to give carbazoles and fused carbazoles in good yields. The scope and limitations of the reaction have been briefly studied. The nature of N-protection of the furoindolones (cf. 7) plays a major role in the success of annulation.     

Characterization of Citrus aurantifolia bioactive compounds and their inhibition of human pancreatic cancer cells through apoptosis

In the current study, we have isolated and purified five putative compounds from lime (Citrus aurantifolia Swingle) seeds using Soxhlet extraction and chromatographic separation. The purity and structures of the isolated compounds were identified by TLC, HPLC and mass spectra as limonin, limonexic acid (LNA), isolimonexic acid (ILNA), β-sitosterol glucoside (SG) and limonin glucoside (LG). These putative compounds exhibited significant inhibition of Panc-28 cells with IC₅₀ values in the range of 18–42 µM in MTT assay after incubation for 72 h, which was confirmed by viable cell count. Further, induction of apoptosis was confirmed through annexin-FITC staining of the cells and expression of apoptosis related proteins was also studied to understand the mechanism. Expression of apoptosis related protein showed apoptosis through induction of p53 by, p21 dependent manner and cytochrome-c mediated caspases driven intrinsic pathway. Expression of apoptosis favoring proteins in cells treated with isolated compounds were in the order of ILNA > LNA > SG > Limonin > LG based on the expression ratio of bax/bcl2. These results were further supported through fluorescent probed microscopic images. To the best of our knowledge, this is the first report on isolation and identification of LNA, SG and LG from lime and their mechanism of inhibition of human pancreatic cancer cells.     

A General Approach to Angucyclines: Synthesis of Hatomarubigin A, Rubiginone B2, Antibiotic X-1488E, 6-Hydroxytetrangulol, and Tetrangulol

Hatomarubigin A was prepared in 41% yield in a single procedure from acyl naphthoquinone 15 and 5-methylcyclohexane-1,3-dione (16). The net reaction consists of Michael addition to an acyl quinone followed by intramolecular aldol condensation. Hatomarubigin A then served as a common intermediate in syntheses of the angucyclinone antibiotics rubiginone B2, antibiotic X-1488E, 6-hydroxytetrangulol, and tetrangulol.