40596-17-6Relevant articles and documents
Controllable Stereoselective Synthesis of (Z)- and (E)-Homoallylic Alcohols Using a Palladium-Catalyzed Three-Component Reaction
Horino, Yoshikazu,Sugata, Miki,Mutsuura, Itaru,Tomohara, Keisuke,Abe, Hitoshi
supporting information, p. 5968 - 5971 (2017/11/10)
Diastereoselective synthesis of (Z)- and (E)-homoallylic alcohols using a Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl benzoates, aldehydes, and aryl stannanes was developed, which provides an alternative method for the allylboration of aldehydes using α, γ-diaryl-substituted allylboronates. Both sets of reaction conditions enable access to either (Z)- or (E)-homoallylic alcohols with good to high alkene stereocontrol. The present method showed good functional group compatibility and generality. Efficient chirality transfer reactions to afford enantioenriched (Z)- and (E)-homoallylic alcohols were also achieved.
Diethylzinc-mediated allylation of carbonyl compounds catalyzed by [(NHC)(PR3)PdX2] and [(NHC)Pd(η3-allyl)Cl] complexes
Flahaut, Alexandre,Toutah, Krimo,Mangeney, Pierre,Roland, Sylvain
experimental part, p. 5422 - 5432 (2010/06/15)
[(NHC)(PR3)PdX2] complexes (NHC = N-heterocyclic carbene) are active precatalysts in the palladium-catalyzed allylation of carbonyl compounds with allylic acetates and diethylzinc. A comparative study examining the catalytic activity of a series of six of these complexes was carried out with allyl and cinnamyl acetates. [(IMeSMe)(PPh3)PdI 2] was found to be the most versatile precatalyst (IMesMe = 1-mesityl-3-methylimidazol-2-ylidene) and the scope of the reaction was investigated with this complex. [(IMeSMe)(PPh3)-PdI2] catalyzes the allylation of aromatic (except 4-nitrobenz-aldehyde) and aliphatic aldehydes (including enolizable aldehydes) with cinnamyl acetate to give the corresponding homoallylic alcohols in 57-98 % yields and dlastereoselectivities ranging from 70:30 to 92:8. The allylation of acetone also takes place under the same conditions, leading to the expected adduct in 63 % yield. The reaction with cyclohexenyl acetate proceeds at room temperature to afford the homoallylic alcohols in 40-78% yields with excellent diastereoselec-tivities (>98:2), but is limited to aromatic aldehydes. An experimental study concerning the mechanism, of the transformation was also carried out. We first demonstrated that the phosphane ligand was not essential for the reaction to take place. [(NHC)Pd(allyl)Cl] complexes are active precatalysts and lead to similar yields in the presence or in the absence of PPh3. Transmetalation of [(NHC)Pd(allyl)Cl] complexes with diethyl- or dimethylzinc, which is a determining step for the mechanism, was studied by 1H NMR spectroscopy. The reaction of [(IPr)Pd(allyl)Cl] with dimethylzinc affords rapidly [(IPr)Pd(η3-allyl)(Me)] but no detectable trace of allylzinc species [IPr = 1, 3-bis(2, 6-diisopropylphenyl)imidazol-2-ylidene]. [(IPr)Pd(η3-allyl)(Me)] was found to be a nucleophilic species able to react smoothly at room temperature with an aldehyde in the absence of zinc to form the corresponding homoallylic alcohol.
Transition-metal-catalyzed sequential cross-coupling of bis(iodozincio)methane and -ethane with two different organic halides
Yoshino, Hideaki,Toda, Narihiro,Kobata, Masami,Ukai, Katsumi,Oshima, Koichiro,Utimoto, Kiitiro,Matsubara, Seijiro
, p. 721 - 726 (2007/10/03)
Bis(iodozincio)methane, prepared from diiodomethane and zinc, reacts with an organic halide in the presence of a transition-metal catalyst to give an iodozinciomethylenated compound; this then reacts with another organic halide to form a C-C bond. The overall process connects two electrophiles with one carbon atom. Bis(iodozincio)ethane can also undergo this transformation, yielding a new stereogenic center. The asymmetric induction of this stereogenic center was investigated by using a chiral palladium catalyst.
