A highly active heterogeneous catalyst, pdmof5, has been prepared, characterized and successfully applied in ligand and copperfree sonogashira coupling reactions. Palladium nanoparticles immobilized on individual calcium. Mechanism of copperfree sonogashira reaction operates. The high thermodynamic stability and specific surface area of mof5 meet the demands for utilization as a catalyst support. The novel aryliodide containing nitroxide, 5iodo1,1,3,3tetramethylisoindolin2yloxyl, 3, was a key intermediate for this. This leads to what is known as the glaser coupling reaction, which is an undesired formation of homocoupling products of acetylene derivatives upon oxidation. A carbopalladation mechanism was ruled out through a series of experiments in which the equivalent of a carbopalladation reaction. A copperfree sonogashira coupling reaction in ionic. Sonogashira coupling project gutenberg selfpublishing. Now, an easy, quick and aerial copperfree methodology for the sonogashira reaction using readily available palladium complexes as catalyst has been reported. If such a sequence could also be accomplished in a onepot fashion, it would streamline the synthesis of borylated aromatic alkynes while allowing access to target molecules bearing the contraelectronic substitution patterns often associated with chb reactions. A mild, copperfree sonogashira coupling of aryl iodides with terminal acetylenes in water under aerobic conditions has been developed.
Reactions carried out under both heterogeneous and homogeneous conditions using distinct au 0, au i, and au iii species reveal that au i is the. Considering the mechanism of the reaction, it is important to note that these. Generally, the sonogashira reaction required cui cocatalyst for the achievement. Here we describe examples where the sonogashira reaction serves as a key coupling step in the convergent synthesis of. The seminal contributions by sonogashira, cassar and heck in mid 1970s on pdcu and pdcatalysed copperfree coupling of acetylenes. The mechanism of the copperfree sonogashira crosscoupling was investigated using a model reaction with differently parasubstituted. Palladium and copper cocatalyzed sonogashira coupling is reported to proceed via two independent catalytic cycles scheme 2. This video looks at the proposed mechanism for the sonogashira coupling reaction. The seminal contributions by sonogashira, cassar and heck in mid 1970s on pdcu and pdcatalysed copperfree coupling of acetylenes with aryl or vinyl halides have evolved in myriad applications. Palladiumcatalyzed copperfree sonogashira coupling. To access a cheminform abstract of an article which was published elsewhere, please select a full text.
Photoactivation of pdcatalyzed sonogashira coupling. Palladiumcatalyzed sonogashira coupling reaction of 2. Introduction sonogashira reaction is the spsp2 carbon cross coupling reaction of terminal alkynes with aryl halides or alkenyl halide. Our group recently reported an efficient protocol for a copperfree sonogashira cross coupling at low temperature, in aqueous medium and. Here we describe examples where the sonogashira reaction serves as a key coupling step in the convergent synthesis of natural products. The most important improvement for the sonogashira coupling is probably to perform this reaction under copper. Simple, efficient copperfree sonogashira coupling of haloaryl carboxylic acids or unactivated aryl bromides with terminal alkynes article pdf available in catalysis communications 9. The protocol we developed employs catalytic amount of copperi, nontoxic ligand bathophenanthroline and is tolerant to a wide range of functional groups and is therefore particulary adapted in the context. The use of an ionic liquid allows for the facile separation and recycling of the catalyst. The use of 1 mol % pdcl2 in the presence of pyrrolidine allows the coupling reaction to proceed at room temperature or 50 c with good to excellent yields. Efficient copperfree sonogashira coupling of aryl chlorides with. A series of pyridine enhanced precatalyst, preparation, stabilisation and initiation peppsi214 nheterocyclic carbene palladiumii precatalysts 146149 have been prepared and employed in copperfree sonogashira coupling reaction. The mixed catalyst system, pdch 3 cn 2 cl 2 ptbu 3 ru2,2.
The sonogashira cross coupling reaction between aryl halides and terminal alkynes was carried out smoothly in water over a thermoregulated ligandpalladium catalyst. Ligand and copperfree sonogashira and heck couplings of. This reaction is an extension to cassar and dieck and heck reactions, that carries coupling with the use of palladium catalyst. The protocol we developed employs catalytic amount of copperi, nontoxic ligand bathophenanthroline and is tolerant to a wide range of functional groups and is therefore particulary adapted in the context of drug discovery. A mild protocol for the copperfree sonogashira coupling of aryl iodides with terminal acetylenes in water under aerobic conditions has been developed. The mechanism of the copperfree sonogashira cross coupling was investigated using a model reaction with differently parasubstituted phenylacetylenes and 4iodobenzotrifluoride as coupling partners and a pd2dba3chcl3. A cuicatalysed sonogashira type cross coupling reaction with aliphatic or aromatic bromoisoxazolines or nalkoxyimidoyl bromides and alkynes is reported. Introduction transition metal catalyzed reactions have evolved as a 15 versatile tool in organic chemistry during the last three decades because of easy carboncarbon bond formation which were.
But the sonogashira reaction uses copper and palladium catalysts continuously. Sonogashira cross coupling chemistry bibliographies. In summary, we have shown that the watersoluble palladiumsalen complex 2 efficiently catalyzes the copperfree sonogashira coupling reaction of aryl iodides with terminal alkynes in water using sodium lauryl sulfate as the surfactant and cs. The proposed mechanism for monoligated precatalysts begins by. Sonogashira couplings enable convergent synthesis strategies, which are of value due to their advantages in 30 efficiency over more linear synthesis strategies. Simple, efficient copperfree sonogashira coupling of. When optimised, the coupling reaction of bromobenzene with phenylacetylene gave a 45% yield of diphenylacetylene within 3. The copperfree sonogashira crosscoupling reaction promoted by. The sonogashira coupling reaction is one of the most widely used methods for the coupling of vinyl or aryl halides with terminal alkynes to form conjugated enynes or aryl alkynes. The palladium catalyzed mechanism begins with oxidative addition of the organohalide to the pd0 to form a pdii complex. Copperfree sonogashira coupling while a copper cocatalyst is added to the reaction to increase reactivity, the presence of copper can result in the formation of alkyne dimers. To address this several reports described copper free sonogashira couplings 2 cu 2 h 2 cucl, nh4oh etoh nh4oh etoh 7. This video gives a broad overview of the sonogashira coupling reaction and how you would go about predicting product for it. These results demonstrate that the sonogashira reaction is suitable for the generation of a wide range of aryl nitroxides of expanded structural variety.
Ebook or pdf edited book email encyclopedia article govt. Two competing mechanisms for the copperfree sonogashira. Interestingly, the utility of the \copperfree sonogashira protocol has subsequently been rediscovered independently by a number of researchers in recent years. The sonogashira cross coupling reaction is the organic reaction of an organohalide with a terminal alkyne to give the coupled product using a palladium catalyst, a copper catalyst, and base. Stille cross coupling reaction palladium catalyst with organotin useful to construct new carboncarbon bonds sonogashira cross coupling reaction palladium catalyzed copper i cocatalyst amine base coupling of terminal alkynes with aryl or vinyl halides. The reaction has become an essential tool in the synthesis of these compounds, which. Occasionally, this reaction is also referred to as the sonogashira hagihara reaction. This work demonstrates that mussel shell waste can be used as an inexpensive and effective support for metal catalysts in coupling reactions, as demonstrated by the successful performance of the pd. Palladiumfree sonogashiratype crosscoupling reaction of. Ligand, copper, and aminefree sonogashira reaction of. Pdf mechanism of copperfree sonogashira reaction operates. The application of the above reaction in a microflow system in conjunction with an imm micromixer was also successful. The sonogashira coupling was proposed in the year 1975 by nobue hagihara, yasuo tohda and kenkichi sonogashira in their publication.
The seminal contributions by sonogashira, cassar and heck in mid 1970s on pd cu and pdcatalysed copperfree coupling of acetylenes. Pdf simple, efficient copperfree sonogashira coupling. An efficient palladiumcatalyzed copperfree sonogashira reaction in water and acetone has been developed under mild conditions. The reactions conditions, mechanistic features and weaknesses of the sonogashira coupling have been discussed. Request pdf copperfree sonogashira coupling reaction with pdcl 2 in water under aerobic conditions a mild protocol for the copperfree sonogashira coupling of aryl iodides with terminal. Several reaction parameters like solvent, base and temperature were evaluated. Optimization of an efficient and sustainable sonogashira.
The role of au 0, au i, and au iii cations in the heterogeneous gold catalyst auceo 2 was investigated with the copper. The coupling of a terminal alkyne and an aromatic ring is the pivotal reaction when talking about applications of the copperpromoted or copperfree sonogashira reaction. Prior to oxidative addition, the 14electron pdl 2 complex is generated through a reductive process known as. Pdf synthesis of 3alkynylselenophene derivatives by a. Copperfree sonogashira crosscoupling reactions catalyzed. Copperfree sonogashira coupling in aminewater solvent. Heterogeneous copperfree sonogashira coupling reaction. Efficient palladiumcatalyzed coupling of aryl chlorides and tosylates with terminal alkynes. Copperfree sonogashira coupling reactions catalyzed by a. Palladiumcatalyzed phosphine, copperfree and aerobic. Sonogashira coupling reaction of terminal alkynes with aryl halides catalyzed over a pd0cui system is one of the most powerful tool in.
This reaction is one of the most effective methods to form new carboncarbon bonds 1 9. Results and discussion investigation of reaction conditions initially the coupling of 4iodoanisole and phenylacetylene was chosen as the model reaction for screening the reaction conditions. Copperfree sonogashira coupling reaction with pdcl 2 in. Two competing mechanisms for the copperfree sonogashira cross coupling reaction 2008 organometallics. In summary, a robust, copperfree sonogashira coupling reaction is. The ligand and copperfree sonogashira reaction of hetaryl halides br and cl with various terminal alkynes and the heck coupling of hetaryl halides br and cl with a series of olefins, catalyzed by palladium nanoparticles supported on newly generated aloh3, were developed. Copperfree sonogashira coupling reaction with pdcl2 in water. Recent advancements and perspectives in coppercatalysed. Mechanistic studies 11 of the copperfree version of the sonogashira coupling have shown that the polarity and hydrogen bonding ability of the solvents are important in accelerating the reaction by stabilizing the ionic intermediates of the catalytic cycle, whereas steric bulk decreases the stabilizing ability of the solvent. Pdf simple, efficient copperfree sonogashira coupling of haloaryl. The copperfree sonogashira crosscoupling reaction promoted by palladium complexes of nitrogencontaining chelating ligands in neat water at room. Copperfree sonogashira coupling reaction with pdcl2 in.
The influence of substituents in aryl bromides, acetylenes, and phosphines. The seminal contributions by sonogashira, cassar and heck in mid 1970s on pdcu and pdcatalysed copperfree coupling of acetylenes with aryl or vinyl halides have evolved in. It is possible that the sonogashira cross coupling of haloaryl carboxylic acids and unactivated aryl bromides with terminal alkynes will be achieved by the methodology above. Mechanism of copperfree sonogashira reaction operates through. Pdf the seminal contributions by sonogashira, cassar and heck in mid 1970s on pdcu and pdcatalysed copperfree coupling of acetylenes with aryl. Sonogashira couplings enable convergent synthesis strategies, which are of value due to their advantages in efficiency over more linear synthesis strategies.
Efficient copperfree pdcl 2 pcy 3 2catalyzed sonogashira coupling of aryl chlorides with terminal alkynes c. The list of cases where the typical sonogashira reaction using aryl halides has been employed is large, and choosing illustrative examples is difficult. Onepot iridium catalyzed ch borylation sonogashira. Copper free palladium catalyst for reaction with aryl halides 15. Cheminform is a weekly abstracting service, delivering concise information at a glance that was extracted from about 200 leading journals. Catalytic cycle of palladium and copper cocatalyzed sonogashira reaction.
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