Heck reaction with heteroaryl halides in the presence of a palladium-tetraphosphine catalyst (original) (raw)
Related papers
Tetrahedron Letters, 2003
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C 3 H 5 )] 2 system catalyses efficiently the Heck reaction of aryl halides with linear alkenes such as pent-1-ene, oct-1-ene or dec-1-ene. Selectivities up to 70% in favour of E-1-arylalk-1-ene isomers can be obtained. In the presence of cyclic alkenes the selectivities of the reactions strongly depends on the ring size. Addition to cyclohexene or cycloheptene led mainly to 1-arylcycloalk-3-ene derivatives. On the other hand, addition to cyclooctene led to 1-arylcycloalk-1-ene adducts.
Ligand and base-free Heck reaction with heteroaryl halides
Tetrahedron Letters, 2011
Pd(CH 3 CN) 2 Cl 2 -catalyzed Heck reaction of different heteroaryl halides with olefins is carried out in the absence of both the ligand and base to obtain the corresponding coupling products in good yields. tional group tolerance, mild reaction conditions, and performance with a variety of aryl halides and olefins make the Heck reaction very attractive in the field of synthetic organic chemistry. Significant advances have been made in the past two decades on the Heck reaction using different phosphine ligands 3 , palladacylces 4 , and non-phosphine Pd-catalysts, such as N-heterocyclic 5 , carbocyclic carbenes 6 , and N, O, S-donor 7 atoms containing Pd-catalysts. However, the industrial application of this reaction is limited owing to the high cost of the ligands and catalysts. Although the first protocol of the Heck reaction of aryl iodides under ligand-free conditions has been known for years 9 , Pd(OAc) 2 in combination with a suitable base has been traditionally used as an effective catalyst for the coupling of aryl bromides with terminal olefins. 10 It has been shown that the palladium catalyst, irrespective of the nature of its precursor, is rapidly reduced to Pd(0) at high temperature, which has a strong tendency to form colloids, 11 and the palladium nanoparticles that are present in these colloids catalyze the Heck reaction. However, the ligand-free approaches are usually limited to aryl iodides and aryl bromides.
Tetrahedron Letters, 2004
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C 3 H 5 )] 2 efficiently catalyses the Heck reaction of alk-1-en-3-ol with a variety of aryl bromides. In the presence of hex-1-en-3-ol or oct-1-en-3-ol, the b-arylated carbonyl compounds were selectively obtained. Linalool and 2-methylbut-3-en-2-ol led to the corresponding 1-arylalk-1-en-3-ol derivatives. Turnover numbers up to 69,000 can be obtained for this reaction. A minor electronic effect of the substituents of the aryl bromide was observed. Similar reaction rates were observed in the presence of activated aryl bromides such as bromoacetophenone and deactivated aryl bromides such as bromoanisole.
3(5)-Pyrazolyl substituted triphenylphosphines as ligands for the palladium catalyzed Heck reaction
Inorganica Chimica Acta, 2006
3(5)-Pyrazolyl substituted triphenylphosphines have been investigated as ligands for the palladium catalyzed Heck reaction of aryl halides with styrene. Catalysts formed in situ from those phosphines and Pd II (OAc) 2 are comparable in activity and selectivity with the corresponding pre-synthesized Pd(II) complexes, while Pd 2 (dba) 3 has turned out to be a less suitable palladium source. Among the ligands investigated, the bidentate P,N-ligand 2-[3(5)-pyrazolylphenyl]diphenylphosphine has shown the highest activities for the coupling of bromobenzene with styrene in the presence of Pd II (OAc) 2. In the presence of 1 equiv. of nBu 4 NI as the additive, unreactive 4chloroacetophenone also undergoes Heck coupling with styrene.
The Heck reaction: mechanistic insights and novel ligands
Polyhedron, 2000
The kinetics of the Heck reaction of aryl iodides with methyl acrylate using phosphane ligands were studied. Triphenylphosphane strongly inhibited the reaction when used in excess over the Pd(0) precatalyst. The rate of reaction was found to be weakly dependent on the concentrations of both the aryl iodide and the alkene. The results indicate that the migratory insertion step is turnover limiting, with the oxidative addition to the aryl iodide being faster but not negligible. Phosphane sulfane hemilabile ligands were found to give good yields and good catalyst stability in Heck reactions.
ChemInform, 2002
A simple and efficient experimental protocol has been developed for the catalytic arylation of alkenes by the air and water stable, and phosphine-free compound PdCl 2 (SEt 2 ) 2 associated with tetrabutyl ammonium bromide. Using this catalytic protocol, aryl iodides and bromides, and electron-poor aryl chlorides are coupled with n-butylacrylate and styrene under relatively mild reaction conditions with high catalytic activity. Reaction vessel ultra-trace amounts (ppt) of this Pd precursor promotes the coupling of iodo benzene with n-butylacrylate with turnover numbers (mol product/mol Pd) up to 10 9 .
On the use of phosphine-free PdCl 2(SEt 2) 2 complex as catalyst precursor for the Heck reaction
Tetrahedron Letters, 2001
A simple and efficient experimental protocol has been developed for the catalytic arylation of alkenes by the air and water stable, and phosphine-free compound PdCl2(SEt2)2 associated with tetrabutyl ammonium bromide. Using this catalytic protocol, aryl iodides and bromides, and electron-poor aryl chlorides are coupled with n-butylacrylate and styrene under relatively mild reaction conditions with high catalytic activity. Reaction vessel ultra-trace
Pd-catalyzed Heck reactions of aryl bromides with 1,2-diarylethenes
Journal of the Brazilian Chemical Society, 2011
Um sistema catalítico composto por Pd(OAc) 2 e P(o-tol) 3 foi aplicado na reação de Heck entre brometos de arila e diariletenos. Utilizando-se K 2 CO 3 como base e DMF como solvente, olefinas triarilsubstituídas foram obtidas com rendimentos de bons a excelentes. Brometos de arila com substituintes eletroretiradores foram menos ativos para a reação de acoplamento Heck e levaram à formação de produto de homoacoplamento em quantidades substanciais, indicando que a adição oxidativa não deve ser a etapa lenta da reação. A presença de substituintes no diarileteno afetou drasticamente a seletividade da reação. Realizou-se também a dupla arilação do estireno, levando diretamente à olefina triarilsubstituída, com rendimento de 73%. A catalytic system composed of Pd(OAc) 2 and P(o-tol) 3 was found to be effective for the Heck reaction of aryl bromides with diarylethylenes. Using K 2 CO 3 as a base and DMF as a solvent, trisubstituted olefins were obtained in good to excellent yields. Aryl bromides containing an electron-withdrawing group in para position were less reactive for the Heck coupling reaction and gave substantial amount of homocoupling by-product suggesting that oxidative addition is not the rate-determining step. Electron withdrawing group substituent in the para position of stilbene affects the regioselectivity of the reaction. In this case, the phenyl group from the Ph-Pd complex migrates preferentially to the same carbon of the double bond to which the phenyl is bonded. Finally, a one pot sequential double Heck arylation of styrene was performed, giving trisubstituted olefin with an overall yield of 73%.