Fused aziridines as sources of azomethine ylides

Green Light Promoted Iridium(III)/Copper(I)-Catalyzed Addition of Alkynes to Aziridinoquinoxalines Through the Intermediacy of Azomethine Ylides

This manuscript describes the development of alkyne addition to the aziridine moiety of aziridinoquinoxalines using dual Ir(III)/Cu(I) catalytic system under green light-emitting diode (LED) photolysis (λmax =525 nm). This mild method features high levels of chemo- and regioselectivity and was used to generate 30 highly functionalized substituted dihydroquinoxalines in 36-98 % yield. This transformation was also carried asymmetrically using phthalazinamine-based chiral ligand to provide 9 chiral addition products in 96 : 4 to 86 : 14 e.r. The experimental and quantum chemical explorations of this reaction suggest a mechanism that involves Ir(III)-catalyzed triplet energy transfer followed by a ring-opening reaction ultimately leading to the formation of azomethine ylide intermediates. These azomethine intermediates undergo sequential protonation/copper(I) acetylide addition to provide the products.

Non-pericyclic cycloaddition of gem-difluorosubstituted azomethine ylides to the CO bond: computational study and synthesis of fluorinated oxazole derivatives

The cycloaddition of α,α,α-trifluoroacetophenones with gem-difluoro-substituted azomethine ylides, generated from N-benzhydrylideneamines and difluorocarbenes, occurs regioselectively to give fluorinated oxazolidines.