Versatile Visible-Light-Driven Synthesis of Asymmetrical Phosphines and Phosphonium Salts

Asymmetrically substituted tertiary phosphines and quaternary phosphonium salts are used extensively in applications throughout industry and academia. Despite their significance, classical methods to synthesize such compounds often demand either harsh reaction conditions, prefunctionalization of starting materials, highly sensitive organometallic reagents, or expensive transition-metal catalysts. Mild, practical methods thus remain elusive, despite being of great current interest. Herein, we describe a visible-light-driven method to form these products from secondary and primary phosphines. Using an inexpensive organic photocatalyst and blue-light irradiation, arylphosphines can be both alkylated and arylated using commercially available organohalides. In addition, the same organocatalyst can be used to transform white phosphorus (P₄) directly into symmetrical aryl phosphines and phosphonium salts in a single reaction step, which has previously only been possible using precious metal catalysis.     

Synthesis and Structure of Quaternary Phosphonium Salts Based on Phosphorylated Sterically Hindered Phenols

Russian Journal of General Chemistry - A procedure was developed for the synthesis of quaternary phosphonium salts with two phosphorus atoms [P(III) and P(V)] based on phosphorylated hindered...     

Isolation of (R)-(+)-Pulegone from the European Pennyroyal Mint, Mentha Pulegium

Students obtain, via steam distillation, pennyroyal essential oil that is analyzed by capillary gas chromatography—mass spectrometry. TLC experiments establish conditions for preparative scale purification of the major oil component via flash column chromatography. The terpene obtained, (R)-(+)-pulegone, is characterized spectroscopically, employing at a minimum mass spectral molecular ion and fragmentation patterns, IR, and 300-MHz ¹H NMR. Optionally, ¹³C and 2-D correlation NMR spectra can be utilized to enable unambiguous assignment of all C and H resonances. The project has been successfully incorporated into our upper-level advanced organic chemistry laboratory. The experiment provides opportunities for instruction in and experience with a wide variety of chromatographic and spectroscopic methods. Further, it centers on a plant and natural product well suited for the discussion of contemporary health care issues surrounding nontraditional/alternative medicine and herbal remedies.     

Synthesis of (+)-(R)-Tiruchanduramine

The absolute stereochemistry of the marine alkaloid (+)-(R)-tiruchanduramine was established via a convergent total synthesis in six steps and 15.5% overall yield from Fmoc-D-Dab(Boc)-OH.     

Synthesis of Sterically Hindered Secondary and Tertiary Alkyl(Aryl)Phosphines

Cross coupling of silylphosphines with 2-halobenzenecarboxylates or 2-halophenyl ethers, catalyzed with zero-valent palladium complexes can not be used as a procedure for preparing sterically hindered tertiary phosphines. The latter compounds can be successfully prepared by means of phosphorylation of corresponding o-lithiated derivatives.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 2, 2005, pp. 239–243.Original Russian Text Copyright © 2005 by Veits, Neganova, Vinogradova.     

(1R,6R)-(+)-鱼腥藻毒素的合成

鱼腥藻毒素(Anatoxin-a)是自兰藻类水华鱼腥藻(Anabaena flos-aquae)中分离的一种氮杂双环胺类生物碱,其化学结构及绝对构型经X光晶体衍射法测定分析为:(1R,6R)(+)-2-乙酰基-9-氮双环[4.2.1]壬-2-烯,简称为AnTX-a。     

Enantiodivergent Syntheses of (R)- and (S)-3,5-Dimethylcyclohex-2-en-1-ones from (R)-Pulegone

R-(+)-pulegone (1) is transformed to (R)-5-methyl-2-(phenylsulfinyl)cyclohexanone (5) (65%, 3 steps). Sulfoxide 5 is converted to R-(-)-3,5-dimethylcyclohex-2-en-1-one (4) (53%, 4 steps) and S-(+)-4 (26%, 3 steps).     

A Convenient Synthesis of (R)-(+)-Perillaldehyde

A short and efficient synthesis of the commercially unavailable (R)-(+) isomer of perillaldehyde from (+)-limonene oxide has been developed.     

Cyclic Voltammetry of Metallic Acetylacetonate Salts in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents

Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 mol·L^?1 for the most soluble salts, some were found to display encouraging quasi-reversible electrochemical kinetics. For instance, the diffusion coefficients of copper(II) acetylacetonate and iron(III) acetylacetonate in the trifluoroacetamide based DES are 1.14 × 10^?8 and 5.12 × 10^?9 cm²·s^?1, which yields rate constants of 3.16 × 10^?3 and 8.43 × 10^?6 cm·s^?1, respectively. These results are better than those obtained with the DESs prepared from ethylene glycol. The poor kinetics of the iron(III) acetylacetonate system was possibly due to the hygroscopic nature of the DESs that resulted in a continuous build-up of moisture in the system in spite of the maintenance of an inert atmosphere by means of a plastic glove bag. Further work is thus envisaged in an inert dry box that could lead to H-type glass cell charge/discharge experiments in the future.     

(+)-(1S,2S,5R)-8-联苯薄荷醇的合成

以(R)-( )-pu legone为起始原料,经1,4-加成,还原两步反应合成了手性辅助试剂( )-(1S,2S,5R)-8-联苯薄荷醇及其差向异构体(-)-(1R,2S,5R)-8-联苯薄荷醇,总产率95%。其结构经1H NMR,13C NMR,IR,MS和X-射线衍射仪表征。     

聚合物负载季鏻盐催化 CO2 与环氧化物的环加成反应

 制备了聚合物负载的季鏻盐催化剂, 并用于 CO₂ 与环氧氯丙烷环加成反应中. 采用红外光谱、热分析、原子吸收光谱和扫描电子显微镜等手段测定了催化剂的结构、热性能、磷元素含量和表面形貌等. 考察了 CO₂ 压力、温度、催化剂用量和反应时间等对环加成反应性能的影响. 结果表明, 在催化剂用量为 0.09 g, CO₂ 压力为 4.5 MPa, 于 150 ^oC 反应 6 h 时, 3-氯甲基环碳酸酯收率可达 97.7%, 选择性大于 99%. 且催化剂易分离回收, 重复使用 5 次后产物收率和选择性没有明显下降. 同时探讨了该催化剂上 CO₂ 环加成合成环碳酸酯的可能机理.     

新型手性季鏻盐的合成

以(S)-联萘酚为原料,与三氟甲磺酸酐反应制得联萘酚三氟甲磺酸酯(2);2在Ni(dppp)Cl2催化下与碘甲烷格氏试剂反应得2,2’-二甲基联萘(3);3经溴代反应得2,2’-二溴甲基联萘4;4与1,3-双(二苯基膦)丙烷(dppp)在甲苯中回流合成了一个新型的联萘酚衍生的双中心手性季鏻盐,其结构经1H NMR,31P NMR和FT-IR表征。     

One-Pot Synthesis and Applications of N-Heteroaryl Iodonium Salts

An efficient one-pot synthesis of N-heteroaryl iodonium triflates from the corresponding N-heteroaryl iodide and arene has been developed. The reaction conditions resemble our previous one-pot syntheses, with suitable modifications to allow N-heteroaryl groups. The reaction time is only 30 min, and no anion exchange is required. The obtained iodonium salts were isolated in a protonated form, these salts can either be employed directly in applications or be deprotonated prior to use. The aryl groups were chosen to induce chemoselective transfer of the heteroaryl moiety to various nucleophiles. The reactivity and chemoselectivity of these iodonium salts were demonstrated by selectively introducing a pyridyl moiety onto both oxygen and carbon nucleophiles in good yields.     

Synthesis and structural characterization of enantiopure (2R,5R)-(+)-2,5-dimethylthiolane

Enantiopure (2R,5R)-(+)-2,5-dimethylthiolane was synthesized by cyclization with sodium sulfide of the dimesylate of (2S,5S)-(+)-2,5-hexanediol, which was obtained by baker's yeast (Saccharomyces cerevisiae) reduction of acetonyl acetone in high enantiomeric purity. The structure of the diol and absolute stereochemistry of the sulfone derived from the title molecule were determined by X-ray crystal structure analysis.     

以活性炭为基材负载季鏻盐多孔碳材料的制备与表征

以市售普通活性炭为碳源,先对其进行强碱活化处理制得多孔碳材料,再经硝酸氧化后,通过水热溶剂法将季鏻阳离子负载于多孔碳上,得到功能化的多孔碳材料。通过比表面积(BET)、热重分析(TGA)、X射线衍射(XRD)、高分辨透射电镜(HRTEM)以及ζ电位对其形貌和结构进行分析,并对其抗菌活性进行表征。结果表明,该方法成功合成了功能化多孔碳材料,该碳材料在水溶液中具有较好的分散性、稳定性和荷电性,并对大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)具有良好的抗菌活性。     

One-Pot Synthesis of 3-(Trimethylsilyl)propynamides

A highly efficient one-pot procedure was developed for the synthesis of 3-trimethylsilylpropynamides by acylation of amines with trimethylsilylpropynoyl chloride generated in situ. Selective N-acylation and N,O-bis-acylation of ß-amino alcohols with formation of, respectively, N-(hydroxyalkyl)propynamides and 2-methyl-2-[3-(trimethylsilyl)propynoylamino]propyl 3-(trimethylsilyl)propynoate were accomplished with high yields.     

Synthesis and Antimicrobial Activity of Poly (Oxyethylene)S Functionalized with Quaternary Phosphonium End Groups

Abstract

Poly(oxyethylene)s functionalized with quaternary phosphonium end groups were obtained by converting terminal hydroxyl end groups into phosphoniurn ion groups in the polymer-analogous reactions with phosphines and hydrogmu chloride. The products were characterized by: IR, UV. H NMR spectroscopy, thin-layer chromatography.     

Synthesis of S(+) and R(-)-3-(2-aminopropyl)indole from ethyl-D- and L-tryptophanate

A stereospecific requirement for hallucinogenesis applies to certain molecules containing an asymmetric center. Thus, only the R-isomers of substituted phenylisopropylamines and lysergic acid diethylamide are psychotomimetic. The enantiomers of a minor hallucinogen, S(+)- and R(-)-3-(2-aminopropyl)indole (α-methyltryptamine) ( 6a and 6b ) were synthesized via a 5-step manipulation from D - and L -tryptophan ethyl ester hydrochloride, respectively. Optical purity of these two isomers was determined by pmr spectroscopy of their complexes with a europium chiral shift reagent using the indole C₂ H signal.