60834-63-1Relevant academic research and scientific papers
Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands
Dilauro, Giuseppe,Azzollini, Claudia S.,Vitale, Paola,Salomone, Antonio,Perna, Filippo M.,Capriati, Vito
supporting information, p. 10632 - 10636 (2021/04/09)
Pd-catalyzed Negishi cross-coupling reactions between organozinc compounds and (hetero)aryl bromides have been reported when using bulk water as the reaction medium in the presence of NaCl or the biodegradable choline chloride/urea eutectic mixture. Both C(sp3)-C(sp2) and C(sp2)-C(sp2) couplings have been found to proceed smoothly, with high chemoselectivity, under mild conditions (room temperature or 60 °C) in air, and in competition with protonolysis. Additional benefits include very short reaction times (20 s), good to excellent yields (up to 98 %), wide substrate scope, and the tolerance of a variety of functional groups. The proposed novel protocol is scalable, and the practicability of the method is further highlighted by an easy recycling of both the catalyst and the eutectic mixture or water.
Mechanistic Study and Development of Catalytic Reactions of Sm(II)
Maity, Sandeepan,Flowers, Robert A.
supporting information, p. 3207 - 3216 (2019/02/19)
Samarium diiodide (SmI2) is one of the most widely used single-electron reductants available to organic chemists because it is effective in reducing and coupling a wide range of functional groups. Despite the broad utility and application of SmI2 in synthesis, the reagent is used in stoichiometric amounts and has a high molecular weight, resulting in a large amount of material being used for reactions requiring one or more equivalents of electrons. Although few approaches to develop catalytic reactions have been designed, they are not widely used or require specialized conditions. As a consequence, general solutions to develop catalytic reactions of Sm(II) remain elusive. Herein, we report mechanistic studies on catalytic reactions of Sm(II) employing a terminal magnesium reductant and trimethylsilyl chloride in concert with a noncoordinating proton donor source. Reactions using this approach permitted reductions with as little as 1 mol % Sm. Mechanistic studies provide strong evidence that during the reaction, SmI2 transforms into SmCl2, therefore broadening the scope of accessible reactions. Furthermore, this mechanistic approach enabled catalysis employing HMPA as a ligand, facilitating the development of catalytic Sm(II) 5-exo-trig ketyl olefin cyclization reactions. The initial work described herein will enable further development of both useful and user-friendly catalytic reactions, a long-standing, but elusive goal in Sm(II) chemistry.
Aza versus Oxophilicity of SmI2: A Break of a Paradigm
Maity, Sandeepan,Flowers, Robert A.,Hoz, Shmaryahu
supporting information, p. 17070 - 17077 (2017/11/13)
Ligands that coordinate to SmI2 through oxygen are prevalent in the literature and make up a significant portion of additives employed with the reagent to perform reactions of great synthetic importance. In the present work a series of spectroscopic, calorimetric and kinetic studies demonstrate that nitrogen-based analogues of many common additives have a significantly higher affinity for Sm than the oxygen-based counterparts. In addition, electrochemical experiments show that nitrogen-based ligands significantly enhance the reducing power of SmI2. Overall, this work demonstrates that the use of nitrogen-based ligands provides a useful alternative approach to enhance the reactivity of reductants based on SmII.
Oxygen Activated, Palladium Nanoparticle Catalyzed, Ultrafast Cross-Coupling of Organolithium Reagents
Heijnen, Dorus,Tosi, Filippo,Vila, Carlos,Stuart, Marc C. A.,Elsinga, Philip H.,Szymanski, Wiktor,Feringa, Ben L.
supporting information, p. 3354 - 3359 (2017/03/17)
The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents. The applicability of this method was showcased by the synthesis of the [11C]-labeled PET tracer celecoxib.
Direct catalytic cross-coupling of organolithium compounds
Giannerini, Massimo,Fananas-Mastral, Martin,Feringa, Ben L.
, p. 667 - 672 (2013/08/23)
Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern synthetic chemistry. However, the high reactivity and poor selectivity of common organolithium reagents have largely prohibited their use as a viable partner in direct catalytic cross-coupling. Here we report that in the presence of a Pd-phosphine catalyst, a wide range of alkyl-, aryl- and heteroaryl-lithium reagents undergo selective cross-coupling with aryl- and alkenyl-bromides. The process proceeds quickly under mild conditions (room temperature) and avoids the notorious lithium halogen exchange and homocoupling. The preparation of key alkyl-, aryl- and heterobiaryl intermediates reported here highlights the potential of these cross-coupling reactions for medicinal chemistry and material science.
Making a difference on excited-state chemistry by controlling free space within a nanocapsule: Photochemistry of 1-(4-alkylphenyl)-3-phenylpropan-2-ones
Sundaresan, Arun Kumar,Ramamurthy
, p. 3575 - 3578 (2008/02/12)
The free space within a reaction cavity plays a determining role during the excited-state reaction of 1-(4-alkylphenyl)-3-phenylpropan-2-ones included within a capsule formed by two molecules of a deep cavity cavitand. By controlling the free space within the reaction cavity through remote alkyl substitution on the reactant ketone it is possible to control the yield of the rearrangement product shown above.
Synthesis and characterization of stilbene derivatives for possible incorporation as smart additives in polymers used as packaging films
Day, Gary M.,Howell, Owen T.,Metzler, Michael R.,Woodgate, Paul D.
, p. 425 - 434 (2007/10/03)
Several series of stilbene derivatives for possible use as smart additives in polymers used as packaging films have been prepared and characterized. Differential scanning calorimetry was performed on some of the stilbenes in order to determine any liquid crystal properties. Those compounds which had multiple phase transitions were also shown to have two liquid crystalline phases according to optical microscopy.
Synthesis and antirhinovirus activity of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)-9H-purines
Kelley,Linn,Selway
, p. 1757 - 1763 (2007/10/02)
A series of 6-(dimethylamino)-2-(trifluoromethyl)-9-(substituted benzyl)purines was synthesized and tested for antirhinovirus activity. Most of the compounds were synthesized by alkylation of 6-chloro-2-(trifluoromethyl)-9H-purine with the appropriate benzyl halide followed by displacement of the chloro group with dimethylamine. Alternatively, 6-(dimethylamino)-2-(trifluoromethyl)purine was alkylated with the appropriate benzyl halide. Although several different aryl substituents provided compounds with IC50's = 0.03 μM against rhinovirus serotype 1B, no congener was significantly more active than the parent 2. Twenty-three compounds were tested against 18 other serotypes, but none exhibited a uniform profile of activity.
Surfactant and Hydrophobic Derivatives of trans-Stilbenes as Probes of Vesicle and Micelle Solubilization Sites. Studies Using Fluorescence and Photoisomerization as Probes
Suddaby, Brian R.,Brown, Patti E.,Russell, John C.,Whitten, David G.
, p. 5609 - 5617 (2007/10/02)
An investigation of the fluorescence and photoisomerization of several surfactant trans-stilbene derivatives in aqueous micelles and vesicles is reported.The temperature dependence of Φf was determined for several media over the range 5-70 deg C.The results present a picture of similar micellar solubilization sites for the trans-stilbene chromophore in every case; the micelle is "seen" by the stilbene as a moderately viscous fluid medium with slightly higher values for Φf and slightly reduced Φt->c compared to nonviscous homogeneous solutions.For vesicles considerably more complex behavior is observed.Generally Φf is considerably higher than in solution and Φt->c is much lower.Several, but not all, of the surfactant and hydrophobic stilbenes show a sharp sensitivity in Φf as a function of T when passing through Tc, the vesicle phase transition temperature.Arrhenius plots for the process competing with fluorescence as a function of temperature show relatively high values for Ea and log A, above Tc, consistent with the high temperature phase providing a microenvironment for the stilbene chromophore like a viscous solvent.Below Tc, the variation of Φf gives much lower values for EA and log A which suggest escape from the fluorescence state is "order limited" rather than viscosity dominated.These results suggest that the low-temperature phase of vesicles presents an environment for the stilbene chromophore more like an inclusion complex than a fluid medium.The effect of cholesterol addition on DODAC vesicles containing the stilbenes is to increase fluidity below Tc and to effectively increase viscosity above Tc.
