RESUMEN
A highly enantioselective allylation of benzofuran-2(3H)-ones is achieved under Pd catalysis by taking full advantage of the structural modularity of ion-paired chiral ligands.
Asunto(s)
Compuestos Alílicos/química , Benzofuranos/química , Paladio/química , Catálisis , Iones , Ligandos , Estructura Molecular , EstereoisomerismoRESUMEN
A metal-free organic carbazole-pyrimidine dye exhibiting phosphorescence-fluorescence dual emission was developed into a white-light emission-switching system. The two crystal polymorphs obtained by breaking the molecular symmetry responded to the external stimuli of heating, vapor-fuming, and mechanical grinding, resulting in a tricolor switching system that includes white-light emission.
RESUMEN
The first highly E- and enantioselective allylic alkylation of prochiral carbon nucleophiles with 1,2-disubstituted allylic carbonates is reported. The key to the successful development of this protocol is the ability of modular ion-paired chiral ligands to simultaneously control the E/Z selectivity and enantioselectivity.
RESUMEN
Conventional chiral ligands rely on the use of a covalently constructed, single chiral molecule embedded with coordinative functional groups. Here, we report a new strategy for the design of a chiral ligand for asymmetric transition-metal catalysis; our approach is based on the development of an achiral cationic ammonium-phosphine hybrid ligand paired with a chiral binaphtholate anion. This ion-paired chiral ligand imparts a remarkable stereocontrolling ability to its palladium complex, which catalyses a highly enantioselective allylic alkylation of α-nitrocarboxylates. By exploiting the possible combinations of the achiral onium entities with suitable coordinative functionalities and readily available chiral acids, this approach should contribute to the development of a broad range of metal-catalysed, stereoselective chemical transformations.