Heck reactions of aryl bromides with alk-1-en-3-ol derivatives catalysed by a tetraphosphine/palladium complex (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.
ChemInform, 2006
Through the use of [PdCl(C 3 H 5 )] 2 /cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction using 2-or 3-subtituted allylic alcohols. With these sterically congested alkenes, the selective formation of b-aryl ketones was observed when appropriate reaction conditions were used. The influence of the functional group on the aryl bromide and of the base on the selectivity is remarkable. With several substrates, much higher selectivities were obtained using NaHCO 3 instead of K 2 CO 3 as base. Furthermore, this catalyst can be used at low loading with several substrates. q
Tetrahedron, 2006
Through the use of [PdCl(C 3 H 5 )] 2 /cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of aryl bromides undergoes Heck reaction using 2-or 3-subtituted allylic alcohols. With these sterically congested alkenes, the selective formation of b-aryl ketones was observed when appropriate reaction conditions were used. The influence of the functional group on the aryl bromide and of the base on the selectivity is remarkable. With several substrates, much higher selectivities were obtained using NaHCO 3 instead of K 2 CO 3 as base. Furthermore, this catalyst can be used at low loading with several substrates. q
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%.
Highly efficient Heck olefin arylation in the presence of iminophosphine–palladium(0) complexes
Journal of Molecular Catalysis A: Chemical, 2005
The Heck coupling of aryl bromides with olefins such as styrene or butyl acrylate is efficiently catalysed by the iminophosphine-palladium(0) complex [Pd(dmfu)(P-N)] (dmfu = dimethyl fumarate; P-N = 2-(PPh 2 )C 6 H 4 -1-CH NC 6 H 4 OMe-4) (1) in polar solvents. With activated aryl bromides such as 4-bromoacetophenone turnover numbers of up to 20,000 can be achieved at 140 • C in 2 h. The presence of electron-donating groups leads to decreased reaction rates, nevertheless, high substrate conversions can be obtained in reasonable reaction times. Kinetic studies indicate that complex 1 is only a precursor of the actual catalytic species. Experiments aimed to demonstrate the intervention of metallic palladium did not lead to conclusive findings.
Heck reaction with heteroaryl halides in the presence of a palladium-tetraphosphine catalyst
Tetrahedron Letters, 2002
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/ 1 2 [PdCl(C 3 H 5 )] 2 system catalyses efficiently the Heck reaction of heteroaryl halides with n-butyl acrylate, styrene, vinylpyridine and vinyl ether derivatives. High turnover numbers can be obtained for the reactions with halo pyridines, quinolines, furans or thiophenes.
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.
Acetylation of N -Heteroaryl Bromides via PdCl 2 /( o -tolyl) 3 P Catalyzed Heck Reactions
Synthesis, 2008
A new user-friendly and convenient method for the acetylation of N-heteroaryl bromides is described. This process is based on the palladium-catalyzed olefination of an N-heteroaryl bromide with butyl vinyl ether, followed by acid hydrolysis of the intermediate heteroaryl vinyl ether in situ. Isopropanol at 85°C, in the presence of K 3 PO 4 •3H 2 O (2 equiv), PdCl 2 (2 mol%) and (otolyl) 3 P (4 mol%), provided the best conditions, giving yields of Nheteroaryl bromides up to 75%.