Dimethylformamide as a carbon monoxide source in fast palladium-catalyzed aminocarbonylations of aryl bromides
TL;DR: The carbonylation procedure reported herein, which relies on the in situ generation of carbon monoxide, serves as a convenient alternative to othercarbonylation methods and is particularly applicable to small-scale reactions where short reaction times are desired and the direct use of carbonmonoxide gas is impractical.
Abstract: Dimethylformamide (DMF) acts as an efficient source of carbon monoxide and dimethylamine in the palladium-catalyzed aminocarbonylation (Heck carbonylation) of p-tolyl bromide to provide the dimethylamide. Addition of amines to the reaction mixture in excess delivers the corresponding aryl amides in good yields. The amines employed, benzylamine, morpholine, and aniline, all constitute good reaction partners. The reaction proceeds smoothly with bromobenzene and more electron-rich aryl bromides, but electron-deficient aryl bromides fail to undergo aminocarbonylation. The reactions are conducted at 180-190 degrees C for 15-20 min with microwave heating in a reaction mixture containing imidazole and potassium tert-butoxide: the latter is required to promote decomposition of the DMF solvent at a suitable rate. The beneficial effects of controlled microwave irradiation as an energy source for the rapid heating of the carbonylation reaction mixture are demonstrated. The carbonylation procedure reported herein, which relies on the in situ generation of carbon monoxide, serves as a convenient alternative to other carbonylation methods and is particularly applicable to small-scale reactions where short reaction times are desired and the direct use of carbon monoxide gas is impractical.
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TL;DR: This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.
Abstract: Although fire is now rarely used in synthetic chemistry, it was not until Robert Bunsen invented the burner in 1855 that the energy from this heat source could be applied to a reaction vessel in a focused manner. The Bunsen burner was later superseded by the isomantle, oil bath, or hot plate as a source for applying heat to a chemical reaction. In the past few years, heating and driving chemical reactions by microwave energy has been an increasingly popular theme in the scientific community. This nonclassical heating technique is slowly moving from a laboratory curiosity to an established technique that is heavily used in both academia and industry. The efficiency of "microwave flash heating" in dramatically reducing reaction times (from days and hours to minutes and seconds) is just one of the many advantages. This Review highlights recent applications of controlled microwave heating in modern organic synthesis, and discusses some of the underlying phenomena and issues involved.
3,044 citations
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TL;DR: The recent academic developments in palladium-catalyzed carbonylation reactions of aromatic halides in the presence of various nucleophiles are summarized and the first industrial processes are summarized.
Abstract: Palladium-catalyzed carbonylation reactions of aromatic halides in the presence of various nucleophiles have undergone rapid development since the pioneering work of Heck and co-workers in 1974, such that nowadays a plethora of palladium catalysts are available for different carbonylative transformations. The carboxylic acid derivatives, aldehydes, and ketones prepared in this way are important intermediates in the manufacture of dyes, pharmaceuticals, agrochemicals, and other industrial products. In this Review, the recent academic developments in this area and the first industrial processes are summarized.
1,177 citations
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TL;DR: A strategy based on assembling metal ions and organic carboxylate links has been applied for the design and synthesis of a new class of porous, truncated tetrahedral and heterocuboidal polyhedra, whose pore size and functionality can be systematically varied.
Abstract: A strategy based on assembling metal ions and organic carboxylate links has been applied for the design and synthesis of a new class of porous, truncated tetrahedral and heterocuboidal polyhedra, whose pore size and functionality can be systematically varied. The synthesis of this series of metal-organic polyhedra (MOPs) employs sulfate-capped oxygen-centered iron-carboxylate trimers, Fe3O(CO2)3(-)(SO4)3, as rigid nodes separated by linear (phenyl, biphenyl, terphenyl, and tetrahydropyrene) or trigonal (benzenetriphenyl) links to yield five highly crystalline polyhedra of general formula [NH2(CH3)2]8[Fe12O4(-)(SO4)12(link)x(py)12].G (x = 6 for linear or 4 for trigonal, py = pyridine, G = guests). In this series, the size of each polyhedron has been varied from 20.0 to 28.5 A (on edge), and the corresponding pore diameter from 7.3 to 13.3 A. Gas sorption isotherms were measured for three members of this series to reveal significant uptake of gases (N2, Ar, CO2, H2, CH4) and benzene and exhibit Type I sorption behavior that is indicative of permanent porosity. The apparent surface areas for these compounds range from 387 to 480 m(2)/g.
573 citations
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TL;DR: This minireview describes carbonylation reactions that can be conducted without the direct use of carbon monoxide, which provide reliable and accessible tools for synthetic organic chemists.
Abstract: Progress in organometallic catalysis began with the discovery of the Roelen reaction (hydroformylation with carbon monoxide and hydrogen) in 1938 and the Reppe reaction (hydrocarboxylation with carbon monoxide and water) in 1939. Since then, carbonylation chemistry by using carbon monoxide has occupied a central position in organometallic chemistry, as it relates to organic synthesis. There is, however, the problem of using gaseous carbon monoxide (a toxic greenhouse gas) in this chemistry. Recently, some strategies that address this issue have appeared. This minireview describes carbonylation reactions that can be conducted without the direct use of carbon monoxide. These carbonylation reactions provide reliable and accessible tools for synthetic organic chemists.
475 citations
References
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TL;DR: The last 15 years of hydroformylation and carbonylation chemistry are reviewed in this article, including technical and commercial aspects, and the authors present a review of the most relevant papers.
Abstract: The last 15 years of hydroformylation and carbonylation chemistry are reviewed, including technical and commercial aspects.
712 citations
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TL;DR: The CSIRO continuous microwave reactor (CMR) and microwave batch reactor (MBR) were developed for organic synthesis and operated at temperatures up to 200°C (1400 kPa) and 260°C(10 MPa) respectively as discussed by the authors.
Abstract: Microwave-assisted organic chemistry is reviewed in the context of the methods employed. A range of technical difficulties indicated that specifically designed reactors were required. Hence, the CSIRO continuous microwave reactor (CMR) and microwave batch reactor (MBR) were developed for organic synthesis. On the laboratory scale, they operated at temperatures (pressures) up to 200°C (1400 kPa) and 260°C (10 MPa), respectively. Advantages and applications of the units are discussed, along with safety issues. Features include the capability for rapid, controlled heating and cooling of reaction mixtures, and elimination of wall effects. Concurrent heating and cooling, and differential heating were unique methodologies introduced to organic synthesis through the MBR. Applications of the microwave reactors for optimizing high-temperature preparations, e.g, the Willgerodt reaction and the Fischer indole synthesis, were demonstrated. Water was a useful pseudo-organic solvent, applicable to environmentally benign synthetic chemistry.
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TL;DR: It is believed that the time saved by using focused microwaves is potentially important in traditional organic synthesis but could be of even greater importance in high-speed combinatorial and medicinal chemistry.
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TL;DR: A very potent HIV-1 protease inhibitor (K(i) = 0.
Abstract: Aryl and vinyl nitriles have been prepared in very high yields from the corresponding bromides using palladium-catalyzed reactions with microwave irradiation employed as the energy source. Furthermore, flash heating was used successfully for the conversion of these nitriles into aryl and vinyl tetrazoles by cycloaddition reactions. One-pot transformation of aryl halides directly to the aryl tetrazoles could be accomplished both in solution and on solid support. All reactions were completed in minutes rather than in hours or days as previously reported with the standard thermal heating technique. A very potent HIV-1 protease inhibitor (Ki = 0.56 nM), comprising two tetrazole heterocycles as carboxyl group bioisosteres, was prepared in one pot by microwave-promoted cyanation of a bromo precursor and a subsequent cycloaddition reaction. The temperature−time profiles at 13, 20, and 60 W magnetron input power in DMF are presented.
256 citations