60674-49-9Relevant articles and documents
Insertion reactions of allenes with palladium aryl complexes [PdI(Ph)(PPh3)]2 and PdI(Ph)(dppe)
Bai, Tao,Xue, Liqin,Xue, Peng,Zhu, Jun,Sung, Herman Ho-Yung,Ma, Shengming,Wiliams, Ian Duncan,Lin, Zhenyang,Jia, Guochen
, p. 2614 - 2626 (2008)
Treatment of [PdI(Ph)(PPh3)]2 with allenes CH 2=C=CHR (R = CMe3, CO2Et, P(O)(OEt) 2, and SO2Ph) in dichloromethane at room temperature produces a mixture of cis and trans isomers of the π-allyl palladium complexes PdI(η3-CH2C(Ph)CHR)(PPh3) in which the R group is anti to the Ph group. The disubstituted alienes MeCH=C=CHR (R = P(O)(OEt)2 and SO2Ph) similarly react with [PdI(Ph)(PPh3)]2 to give the π-allyl palladium complexes PdI(η3-MeCHC(Ph)CHR)(PPh3) in which the R group is anti and the Me group is syn to the Ph group. PdI(Ph)(dppe) alone was found to be unreactive toward allenes such as CH2=C=CHSO 2Ph and MeCH=C=CHSO2Ph at room temperature. In contrast, in the presence of TIPF6, PdI(Ph)(dppe) readily reacts with allenes CH2=C=CHR (R = CMe3, CO2Et, COPh, and SO 2Ph) and MeCH=C=CHSO2Ph to give the π-allyl palladium complexes [Pd(η3-CH2C(Ph)CHR)(dppe)]PF6 and [Pd(η3-MeCHC(Ph)CHR)(dppe)]PF6, respectively. Although mechanistically possible, vinyl complexes were not observed as the insertion products in all cases. The substituents of allenes appear to have no effect on the reaction pathways, at least for the allenes used in this study. The insertion reactions involving PdI(Ph)(PR3)(allene) have been studied by computational chemistry using the model complex PdI(Ph)(MeCH=C= CHSO2H)(PH3).
Unexpected H2O-induced Ar-X activation with trifluoromethylpalladium(II) aryls
Grushin, Vladimir V.,Marshall, William J.
, p. 4632 - 4641 (2007/10/03)
A series of new complexes [(L-L)Pd(Ar)(CF3)] (L-L = dppe, dppp, tmeda; Ar = Ph, p-Tol, C6D5) have been synthesized and fully characterized in solution and in the solid state. Remarkable Ph-X activation (X = I, Cl) by [(dppe)Pd(Ph)(CF3)] (1) has been found to come about to cleanly produce biphenyl and [(dppe)Pd(Ph)(X)]. This reaction does not take place under rigorously anhydrous conditions but in the presence of traces of water it readily occurs, exhibiting an induction period and being zero order in PhI. As shown by mechanistic studies, the role of water is to promote reduction of small quantities of the Pd(II) complex to Pd(0) which activates the Ph-X bond. Subsequent transmetalation to give diphenyl Pd complexes, followed by Ph-Ph reductive elimination give rise to the observed products. The water-induced reduction to catalytically active Pd(0) has been demonstrated to proceed via both the Pd(II)/P(III) to Pd(0)/P(V) redox mechanism and α-F transfer, followed by facile hydrolysis of the difluorocarbene to carbonyl, migratory insertion, and reductive elimination of PhC(X)O (X = F, OH, or OOCPh). In the absence of H2O and ArX, the diphosphine-stabilized trifluoromethyl Pd phenyl complexes undergo slow Ph-CF3 reductive elimination under reinforcing conditions (xylenes, 145 °C).
An exploratory study of regiocontrol iii the heck type reaction. Influence of solvent polarity and bisphosphine ligands
Ludwig, Maik
, p. 970 - 975 (2008/10/08)
The regiochemistry of the addition of arylpalladium species to styrene and propene has been studied. It was found that for the reaction of P2Pd(Ph)X the counterion X, the polarity of the solvent, and the structure of the bisphosphine ligand ?2 all have an influence. Using bis(diphenylphosphino)ethane as ligand, triflate as counterion, and a moderately polar solvent mixture, 98% selectivity for addition of the phenyl group to the /?-carbon of styrene could be obtained. Finally, using low-temperature NMR, some of the palladium intermediates in the addition could be observed, specifically those where the palladium species is stabilized by ?/3-allylic interaction with a phenyl group.
