Chiral Nanoparticles/Lewis Acids as Cooperative Catalysts for Asymmetric 1,4‐Addition of Arylboronic Acids to α,β‐Unsaturated Amides

Abstract

Cooperative catalysts consisting of chiral Rh/Ag nanoparticles and Sc(OTf)3 have been developed that catalyze asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated amides efficiently. The reaction has been considered one of the most challenging reactions because of the low reactivity of the amide substrates. The new catalysts provide the desired products with outstanding enantioselectivities (>98 % ee) in the presence of low loadings (<0.5 mol %) of the catalyst.

Heterogeneous Rh and Rh/Ag bimetallic nanoparticle catalysts immobilized on chiral polymers

“…Ester 5na , a precursor of (–)-indatraline, was also obtained in good yield with high enantioselectivity (entry 25) 32. Amide substrate 3o reacted with 4-fluorophenylboronic acid ( 4g ) to afford 5og , a precursor of (–)-paroxetine, in good yield with excellent enantioselectivity (entry 26) 21,33…”

Synthetic Organic Transformations of Transition‐Metal Nanoparticles as Propitious Catalysts: A Review

“…Kobayashi group improved the methodology for less reactive amides 155 , by developing cooperative catalyst consisting of chiral Rh/Ag nanoparticles in presence of scandium triflate, a Lewis acid. Arylboronic acids with different electronic demanding functionality were successfully added to enamides in presence of chiral diene 149 (Scheme ) …”

Recent developments in enantioselective lanthanide-catalyzed transformations

“…In another context, Kobayashi et al recently developed cooperative catalysts consisting of a combination of chiral Rh/Ag nanoparticles immobilized on a nanocomposite of polystyrene-based copolymers with cross-linking moieties and carbon black (PI/CB catalyst), with Sc(OTf) 3 to be applied to asymmetric Michael additions of arylboronic acids 34a-h to challenging because low reactive a,b-unsaturated amides 35a-e [21]. The chirality of the catalyst system arose from chiral ligand 36 used at catalyst loading as low as 0.1 mol%.…”