74 research outputs found
Efficiency of Industrially Relevant Atropisomeric Diphosphines in Copper-Catalyzed 1,4-Asymmetric Conjugate Addition of Dialkylzincs to Cyclic or Acyclic Enones or Dienones
International audienceIndustrially relevant atropisomeric diphosphines such as 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP), 6,6'-bis(diphenylphosphino)-2,2',3,3'-tetrahydro-5,5'-bi-1,4-benzodioxin (SYNPHOS), and 5,5'-bis(diphenylphosphino)-2,2,2',2'-tetrafluoro-4,4'-bi-1,3-benzodioxole (DIFLUORPHOS) have demonstrated their efficiency in the copper-catalyzed asym. conjugate addn. of various dialkylzincs to α-aryl enones, α-aryl dienones, and cyclic dienones. Excellent 1,4- or 1,6-regioselectivities and enantioselectivities (up to 97% ee) were attained, even with challenging sterically hindered Michael acceptors
New library of aminosulfonyl-tagged Hoveyda-Grubbs type complexes: Synthesis, kinetic studies and activity in olefin metathesis transformations.
International audienceSeven novel Hoveyda-Grubbs precatalysts bearing an aminosulfonyl function are reported. Kinetic studies indicate an activity enhancement compared to Hoveyda's precatalyst. A selection of these catalysts was investigated with various substrates in ring-closing metathesis of dienes or enynes and cross metathesis. The results demonstrate that these catalysts show a good tolerance to various chemical functions
First rhodium/phosphoramidite complex-catalyzed enantioselective isomerization of allylic alcohols into aldehydes
International audienc
Isolation and Characterization of a Chiral η1-Allyl Palladium DIPPAM Complex: Application to the Enantioselective Pd-Catalyzed Allylic Alkylation
International audienceIn the presence of [Cl(C3H5)Pd]2, diphenylphosphinoazomethinylate salt (DIPPAM) 1a forms an original chiral η1-allyl palladium complex, 2. Precatalyst 2/MgBr2 is an efficient catalyst for asymmetric allylic alkylation, giving good yields and ee's in the reactions of rac-4-acetoxy-2-pentene or rac-3-acetoxy-1,3-diphenyl-1-propene and dimethyl malonate (respectively 77% and 96% yield; 66% and 96% ee). Preliminary mechanistic studies have highlighted the key role of the η1-coordination mode of the allyl fragment
- âŠ