656221-51-1Relevant academic research and scientific papers
Electronic Control of Chiral Quaternary Center Creation in the Intramolecular Asymmetric Heck Reaction
Bucassa, Carl A.,Grossbach, Danja,Campbell, Scot J.,Dong, Yong,Eriksson, Magnus C.,Harris, Robert E.,Jones, Paul-James,Kim, Ji-Young,Lorenz, Jon C.,McKellop, Keith B.,O'Brien, Erin M.,et al.
, p. 5187 - 5195 (2007/10/03)
The Boehringer-Ingelheim phosphinoimidazoline (BIPI) ligands were applied to the formation of chiral quaternary centers in the asymmetric Heck reaction. Several different substrates were examined in detail using more than 70 members of this new ligand class. Hammett relationships were determined through systematic variation of the ligand electronics. All substrates showed essentially the same Hammett behavior, where enantioselectivity increased as the ligands were made more electron-deficient. Ligand optimization has led to catalysts which give the highest enantioselectivities reported to date for these difficult systems.
Palladium complexes of phosphinamine ligands in the intramolecular asymmetric Heck reaction
Kiely, Denis,Guiry, Patrick J.
, p. 545 - 561 (2007/10/03)
The synthesis of two novel cyclisation substrates for the asymmetric intramolecular Heck reaction is reported. Their cyclisation, in addition to a known substrate for cis-decalin formation, were tested with palladium complexes of BINAP and heterobidentate oxazoline-containing ligands. In general BINAP provides a more active catalyst system for the range of substrates tested although excellent enantioselectivities of up to 85% were obtained with the P,N ligands studied. A trend was noted whereby the t-leucine-derived oxazoline ligands were more reactive and enantioselective than the valine-derived analogues. Similarly, the diphenylphosphinoferrocenyloxazoline ligands were more reactive and selective than the corresponding diphenylphosphinophenyloxazoline ligands.
