Cu(OAc)2/FOXAP complex catalyzed construction of 2,5-dihydropyrrole derivatives via asymmetric 1,3-dipolar cycloaddition of azomethine ylides to ethynyl ketones

Abstract

Catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides to ethynyl ketones catalyzed by the Cu(OAc)₂/FOXAP (ferrocenyl oxazolinylphosphine) complex was developed, affording 2,5-dihydropyrrole derivatives in good to excellent yields (up to 99%) and excellent levels of enantioselectivities (up to 98% ee). This highly efficient chiral N,P-ligand/Cu(OAc)₂ catalytic system was also applicable for the 1,3-dipolar cycloaddition of α-arylglycine ester-generated azomethine ylides to ynones, affording exclusive quaternary carbon-containing cis-2,5-dihydropyrroles in excellent enantioselectivities (89–92% ee).