Palladium‐Catalyzed Enantioselective C?H Arylation for the Synthesis of P‐Stereogenic Compounds

A palladium‐catalyzed enantioselective C H arylation of N‐(o‐bromoaryl)‐diarylphosphinic amides is described for the synthesis of phosphorus compounds bearing a P‐stereogenic center. The method provides good enantioselectivities and high yields. The products were readily transformed into P‐chiral biphenyl monophosphine ligands.     

Acyclic Branched α-Fluoro Ketones for the Direct Asymmetric Mannich Reaction Leading to the Synthesis of β-Tetrasubstituted β-Fluoro Amines

The preparation of acyclic β-fluoro amines bearing tetrasubstituted fluorine stereocenters is described via a direct Zn/ProPhenol-catalyzed Mannich reaction. The reaction utilizes branched vinyl or alkynyl α-fluoro ketones that can be coupled with a range of aryl, heteroaryl, vinyl, or cyclopropyl aldimines in high yield and with excellent diastereo- (up to >20:1) and enantioselectivity (up to 99 %). The use of readily cleaved tert-butoxycarbonyl (Boc) or carboxybenzyl (Cbz) imine protecting groups adds utility to the reaction by allowing for easy access to the free amine products under mild and chemoselective reaction conditions.     

A Nickel‐Diamine/Mesoporous Silica Composite as a Heterogeneous Chiral Catalyst for Asymmetric 1,4‐Addition Reactions

A chiral composite material, derived from the deposition of a chiral nickel–diamine complex via wet impregnation to MCM‐41, was shown to be an efficient heterogeneous catalyst for asymmetric 1,4‐addition reactions of 1,3‐dicarbonyl compounds with nitroalkenes, and of nitromethane with alkylidenemalonates. It was discovered that MCM‐41 enhanced the reactivity and improved the stability of the chiral nickel complex that resides within the mesoporous material.