A novel chiral ligand mimicking N-Ar axial chirality, (S)-N-[2-(diphenylphosphanyl)naphthalen-1-yl]-2-(piperidinylmethyl)piperidine, was found to exhibit good enantioselectivity (up to 80% ee) in the asymmetric cross-coupling reaction of 1-phenylethylmagnesium chloride with β-bromostyrene derivatives. Additionally, this type ligand is appealing, because it allows the synthesis of a wide variety of analogues.
aryl bromide groups, the chemoselective asymmetric cross-couplingreaction of the vinylbromide group is observed. This N–Ar axially chiral mimetic-type ligand allows easy synthesis of a wide variety of analogues, and starting from the initial ligand, the enantioselectivity of coupling products is improved by modifying the structure in the ligand.
Development of Chiral (<i>S</i>)-Prolinol-Derived Ligands for Palladium-Catalyzed Asymmetric Allylic Alkylation: Effect of a Siloxymethyl Group on the Pyrrolidine Backbone
A series of novel chiral aminophosphine ligands are designed and readily prepared from (S)-prolinol. The reactivity and selectivity in the palladium-catalyzedasymmetricallylicalkylation of 1,3-diphenyl-2-propenyl acetate with a dimethyl malonate−BSA−LiOAc system using these chiral ligands are evaluated, and the structural elucidation of ligands and palladium complex is also conducted. Moreover,
that N-(tert-butyl)-N-methylanilines 1 have C(aryl)–N(amine) bond axial chirality and succeeded the optical resolution of C–N bond atropisomers of amines 1 by a chiral palladium resolving agent and/or a chiral HPLC method. Finally, we demonstrated the ability of chiral amines 1 as a ligand in palladium-catalyzedasymmetricallylicalkylation of allylic esters with malonates (up to 95% ee).
We synthesized a series of phosphine–olefin-type chiral aminophosphines, and we confirmed that these each exists as two rotamers at the C(aryl)–N(amine) bond. We also investigated the ability of these aminophosphines to act as chiralligands for Pd-catalyzed asymmetricallylicsubstitutionreactions, such as the alkylation of allylic acetates with malonates or indoles, and we found they gave high