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Abstract:Simple Brønsted acids such as p-toluenesulfonic acid monohydrate (PTS) or polymer-bound p-toluenesulfonic acid efficiently catalyze the direct nucleophilic substitution of the hydroxy group of allylic and benzylic alcohols with a large variety of carbon-and heteroatom-centered nucleophiles. Reaction conditions are mild, the process is conducted under an atmosphere of air without the need for dried solvents, and water is the only side product of the reaction.Keywords: alcohols; C À C coupling; nucleophilic substitution; supported catalysts; synthetic methodsThe construction of C À C bonds is a fundamental reaction in organic synthesis and coupling reactions between reactive nucleophiles (NuH) and halides (RX) or related species are one of the most used strategies. In this context, direct substitution of the hydroxy group in alcohols by nucleophiles could be considered as an ideal process because of the wide availability of the starting materials and the generation of H 2 O as the only side product. However, the main limitation of this strategy is that an excess of sulfuric acid, polyphosphoric acid, [1] or a stoichiometric amount of a Lewis acid [2] is required, and so the range of possible nucleophiles is limited. Therefore, the development of catalytic versions of this reaction remains as a major objective of the modern organic chemistry (Scheme 1). Recent advances in this field are based on the use of transition metal complexes as catalysts. Remarkable are the Ru-, [3] Re-, [4] and Au-catalyzed [5] propargylation of nucleophiles with propargylic alcohols, the Tsuji-Trost reaction of allylic alcohols with active methylene compounds, [6] the reaction of secondary benzylic alcohols with different nucleophiles catalyzed by La, Sc, or Hf salts, [7] and the Fe-, or Au-catalyzed arylation of benzylic alcohols.[8] In addition, InCl 3 has emerged as a powerful catalyst to perform direct nucleophilic substitution of allylic and benzylic alcohols. [9] Although the catalytic activation of alcohols is thought to be difficult due to the poor leaving ability of the OH group, we have recently found that simple Brønsted acids like p-toluenesulfonic acid monohydrate (PTS) catalyze the direct nucleophilic substitution of propargylic alcohols.[10] Herein we report a strategy involving simple Brønsted acid-catalyzed activation of allylic and benzylic alcohols as a method for the direct formation of new C À C and C À heteroatom bonds from carbon (active methylene compounds, aromatic and heteroaromatic compounds), nitrogen, sulfur, and oxygen nucleophiles and alcohols. Surprisingly, the Brønsted acid-catalyzed direct substitution of allylic alcohols has not been reported in the literature and so no systematic study has so far been performed. Moreover, in some recent papers this reaction has been reported not to proceed at all. [9b] Despite all these negative forewarnings, we decided to investigate the reaction of allylic alcohol 1a as a model substrate with selected nucleophiles 2-8 under PTS-catalyzed conditions (Sche...

To overcome the power delivery limitations of The optimal design of a HESS has been the topic of many batteries and energy storage limitations of ultracapacitors, papers. Researchers [10][11] have considered a direct parallel hybrid energy storage systems, which combine the two energy connection of the two sources. This setup keeps the same sources, have been proposed. A comprehensive review of the voltage over both sources, which in tur limits the power state of the art is presented. In addition, a method of optimizing delivered form the UC. Other researchers have employed a bithe operation of a battery/ultracapacitor hybrid energy storage system (HESS) is presented. The goal is to set the state of charge directional DC/DC converter placed between the batteries and of the ultracapacitor and the battery in a way which ensures that the UC's [3][4][5][6][7][8][9]. The output of the DC/DC converter is current the available power and energy is sufficient to supply the controlled, and controls the current output out of the battery. drivetrain. By utilizing an algorithm where the states of charge of The UC supplies the remaining power requirement to the load. both systems are tightly controlled, we allow for the overall Finally, some researchers have looked at using a two input bisystem size to reduce since more power is available from a directional DC/DC converter [20][21]. It will be shown that smaller energy storage system. this setup gives the highest efficiency, reliability, and flexibility. A comparison of the topologies in terms of the Index Terms-Batteries Battery-ultracapacitor hybrids power maximum power delivery capability will be presented. The control logic and its effect on the power delivery will be I. INTRODUCTION investigated. The remainder of this paper is organised as follows: in Section II some general characteristics of various Hybrid electric vehicles (HEV) couple the power battery technologies and ultracapacitors will briefly be produced by an internal combustion engine (ICE) and an reviewed; an explanation of the topologies mentioned above is electric motor to propel the vehicle more efficiently. Fuel given in Section III; in Section IV the power delivery economy improvement is obtained by using a smaller ICE (set capabilities of the various topologies with different control to provide the average vehicle power demand), augmented by strategies is explored; finally some conclusions are presented the electric motor (provides power demand transients). The in section V. electric motor is powered by an energy source such a battery II. BATTERY AND UC CHARACTERISTICS or an ultracapacitor (UC). The energy source needs to store adequate energy to meet the averaged demand that is required Batteries and UC's are complex electrochemical systems, from the electric motor under various driving conditions [1]. and a detailed review is beyond the scope of this paper. In addition to the energy requirement, the source needs to be However, there are some electrical properties of these devices able to deliver shor...

Background. The authors evaluated the effects of taxol, a microtubular inhibitor, as a possible radiation sensitizer on the human leukemic cell line (HL‐60). Taxol acts as a mitotic inhibitor, blocking cells in the G2M‐phase of the cell cycle. The differential radiation sensitivity of cells in various phases of the cell cycle has been well recognized. This study was focused on the possible interaction between radiation and a microtubular inhibitor, taxol, in regard to its ability to synchronize cells at the G2M‐phase of cell cycle and, thereby, enhance the radiation sensitivity of the cells. Methods. HL‐60 cells were exposed to 3 × 10−8 M concentrations of taxol for 1 hour at 37°CCfollowed by reculturing for 24 hours in drug‐free medium. The cells were then seeded into 60‐mm diameter plastic dishes at appropriate cell concentrations to estimate their colonyforming efficiency. The radiation dose ranged from 0–400 cGy and was delivered in a single fraction. The cellular survival after treatment with the drug and/or radiation was determined using a soft agar clonogenic assay. Results. When HL‐60 cells were treated with taxol, up to 70% of the cells were blocked in G2M‐phase, as determined by flow cytometric analysis. At the low cytotoxic dose of 3 × 10−8 M, the sensitizing enhancement ratio was 1.48. Conclusions. It appears that taxol has a radiation‐sensitizing effect on HL‐60 cells and deserves further investigation with other cell lines.

Simple Brønsted acids such as p-toluenesulfonic acid monohydrate (PTS) efficiently catalyze a direct substitution of the hydroxyl group in propargylic alcohols with 1,3-dicarbonyl compounds. Selective propargylation or allenylation is obtained depending on the nature of the alkynol. Reactions can be performed in air in undried solvents with water being the only side product of the process. By applying this reaction as the key step, a range of interesting polysubstituted furans can easily be synthesized in a one-pot procedure. [reaction: see text].