A diverse series of chiral bicyclic NHC/Ir complexes were prepared via a previously developed divergent synthesis of chiral imidazolium salts. Among the complexes, 8dz was found to be an excellent catalyst precursor for the Ir-catalyzed asymmetric transfer hydrogenation of ketones. The reaction of ketones with 8dz proceeded smoothly to give corresponding alcohols with high enantioselectivities (up to 98%) and productivities (TON up to 4500).
A couple of planar-chiral ferrocene-fused 4-pyridone derivatives 2a and 2b were synthesized in enantiomerically pure form by scalable asymmetric transformations. Pyridones 2 are versatile precursors to various ferrocene-fused pyridine derivatives, which are useful nucleophilic asymmetric organocatalysts.
The
potential of using chiral bicyclic NHC ligands that exhibit
modularity was investigated in the Cu-catalyzed asymmetric borylation
reaction of α,β-unsaturated esters. After screening for
ligands and optimization of the reaction conditions, the corresponding
products were afforded with good enantioselectivities (up to 85% ee).
Various alkylarylketones are hydrogenated in high yields and with high enantiomeric purity. -(YOSHIDA*, K.; KAMIMURA, T.; KUWABARA, H.; YANAGISAWA, A.; Chem. Commun. (Cambridge) 51 (2015) 84, 15442-15445, http://dx.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.