Iron-Catalyzed 1,4-Phenyl Migration/Ring Expansion of α-Azido N-Phenyl Amides

Abstract

Herein, we report a novel iron-catalyzed skeleton rearrangement of alkyl azides. Upon treatment with FeCl2 and N-heterocyclic carbene SIPr·HCl in the presence of H2O and Et3N, 2-azido-N,N-diphenylamides underwent 1,4-phenyl migration and ring expansion to give azepin-2-ones in good yield. The reaction proceeds via intramolecular nitrene cycloaddition followed by C–N cleavage, water addition, and electrocyclic ring opening.

Room-Temperature CuI-Catalyzed N-Arylation of Cyclopropylamine

“…Moreover, many lead and drug candidates containing the N -(hetero)­aryl cyclopropylamine moiety have been recently designed and synthesized, including potent Takeda G-protein-coupled receptor 5 (TGR5) agonists, an orally active and nonsteroidal farnesoid X receptor (FXR) antagonist, a topoisomerase inhibitor, and a modulator of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (Figure A). (ii) N -(Hetero)­aryl cyclopropylamines are building blocks or key intermediates to access various novel ring systems in organic synthesis, e.g., the photocycloadditions of N -(hetero)­aryl cyclopropylamines to alkenes, alkynes, or bicyclo­[1,1,0]­butanes to design various molecular skeletons (Figure B). − Hence, the development of effective methods for preparing N -(hetero)­aryl cyclopropylamines is necessary and many endeavors have been made regarding this for decades.…”

Photo-Induced Electrophilic Aromatic Substitution of Ferric Acyl Nitrene

“…4 In 2021, Yu and co-workers employed αazido N-phenylamides as nitrene precursors, and through a skeleton rearrangement, a cycloaddition of nitrene with arene and sequential ring expansion towards azepin-2-ones were developed under iron catalysis (Scheme 1, eq a). 5 By altering to iridium catalyst, the use of dioxazolones as nitrene precursors underwent a dearomative ipsocyclization with arene, rather than cycloaddition (Scheme 1, eq b). 6 It is believed that the discrepancy is ascribed to the types of the resulting nitrenes, since various nitrene precursors probably produced singlet or triplet nitrene intermediates.…”