Bulky, electron-rich phosphine ligands with a biphenyl backbone, when combined with Pd(OAc)2, give highly active catalysts for the α-arylation of ketones. The ligand 2-methyl-2‘-dicyclohexylphosphinobiphenyl is particularly effective, and with 0.1−1.0 mol % Pd, a large variety of aryl halides and ketones react efficiently and with high selectivity. For two types of substrates, the ligands BINAP and Xantphos are more effective than the biphenyl-based ligands. It is also shown that K3PO4 can be used as the base in these reactions, and that base-sensitive functional groups are better tolerated if this is used instead of NaO t Bu or NaHMDS. In some cases, α-aryl ketones can be produced without adding a ligand to the reaction. Although the substrate scope of the ligandless conditions is limited, some combinations react in high yield, and in one case, 100 000 turnovers were obtained. The results of experiments on the Pd-catalyzed arylation of diethyl malonate, cyclic 1,3-diketones, and nitroalkanes are also reported.

A new catalyst system for the enantioselective alpha-arylation of ketones is reported. This catalyst, prepared from Pd(2)(dba)(3) and a bulky dialkylphosphino-binaphthyl ligand, is able to effect the asymmetric arylation of ketone enolates with aryl bromides utilizing NaO(t)()Bu as base. These new catalysts enjoy much higher reactivity than previous systems; arylation reactions could be effected at room temperature with only 2 mol % of the Pd catalyst. The coupling of alpha-alkyl-alpha'-protected cyclopentanones proceeded in high yield, and the resulting quaternary stereogenic center was installed in up to 94% ee.

[see reaction]. A protocol for the catalytic asymmetric vinylation of ketone enolates has been developed. Key to the success of this process was the development of new electron-rich chiral monodentate ligands.

Z-Vinylic tellurides, obtained with 100% stereoselectivity by the hydrotelluration of acetylenes, are easily transformed into Z-vinylic higher order cyanocuprates by reaction with preformed Me2Cu(CN)Li2, n-Bu2Cu(CN)Li2, or n-Bu(2-Th)Cu(CN)Li2, with total retention of the double-bond configuration. The resulting vinylic higher order cyanocuprates react with unhindered enones to give the corresponding 1,4-addition products in good yields. Reaction of the vinylic higher order cyanocuprates with monosubstituted epoxides at 0 °C gives the homoallylic alcohols resulting from the attack to the less-substituted carbon atom, while the disubstituted epoxides failed to react. Allylic epoxides react at −78 °C with the vinylic higher order cyanocuprates to give mixtures of 1,2- and 1,4-opening products, the 1,4-product predominating. In all cases the double-bond configuration of the original vinylic telluride was preserved. The vinylic cuprates derived from simple vinylic tellurides and conjugated 1-telluroenynes react with epoxides at 0 °C, while vinylic cuprates derived from conjugated 1-tellurodienes required the addition of 1 equiv of BF3·Et2O to give the homoallylic alcohols on reaction with epoxides. The opening of optically pure epoxides through tellurium/copper transmetalation is stereospecific, giving one single stereoisomer of the corresponding homoallylic alcohol.

p -Methoxyphenyl)tellurium trichloride reacts with terminal acetylenes to give 1-chloro-1-organyl-2-[dichloro(p -methoxyphenyl)telluro] ethenes of Z configuration in good yields. The Z stereochemistry of the addition products suggests that the reaction occurs through a four-centered cyclic transition state. The diorganotellurium dichlorides are reduced to the corresponding tellurides with sodium borohydride.