A chiral N-linked C2-symmetric bidentate phosphoramidite (N-Me-BIPAM) was newly developed for the rhodium-catalyzed enantioselective addition of arylboronicacids to N-sulfonylimines. This ligand achieved high enantioselectivities in a range of 84–99% ee in additions of arylboronicacids to N-tosyl- and N-nosylarylaldimines.
An N-Linked Bidentate Phosphoramidite Ligand (N-Me-BIPAM) for Rhodium-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids to α,β-Unsaturated Ketones
on Shibasaki’s N-linked BINOL was synthesized. This ligand appears to be highly effective for rhodium-catalyzed asymmetric conjugatedaddition of arylboronicacids to α,β-unsaturated enones. The reaction of ortho-substituted arylboronicacid with acyclic and cyclic enones provides the corresponding products in good yields and enantioselectivities.
was suitable for bulkier substrates (sterictuning of the catalyst). Using the La-NMe-linked-BINOL complex, the Michaelreaction of methyl acetoacetate (8a) to 2-cyclohexen-1-one (7b) gave the corresponding Michael adduct 9ba in 82% yield and 92% ee. The linker heteroatom in linked-BINOL is crucial for achieving high reactivity and selectivity in the Michaelreaction of beta-keto esters. The amine moiety