Photoinduced Copper-Catalyzed Cross-Coupling of Acylsilanes with Azoles

Abstract

The transition metal-catalyzed direct coupling reac-tions involving electron-rich Fisher carbene species are largely underdeveloped and remain a big chal-lenge. Here, we report a direct coupling reaction of azoles with Fisher copper carbene species bearing an α-siloxy group, which could be in-situ generated from acylsilanes catalytically under photoirradiation and redox-neutral conditions. This reaction features mild conditions and remarkable heterocycle compat-ibility. Notably, this protocol tolerates a series of azole derivatives, including benzoxazole, benzothia-zole, benzoimidazole, benzoisoxazole, oxazole, oxadi-azole, triazolo[4,3-a]pyridine, purine, caffeine etc., which is highly synthetic useful in organic synthesis and pharmaceutical discovery. Preliminary mecha-nistic studies and kinetic analysis implied a bimetal-lic relay process.

Photoinduced Asymmetric Formal Siloxycarbene Insertion into sp3 C–H Bonds Enabled by Chiral Phosphoric Acid

“…They are a kind of highly reactive intermediate and usually own nucleophilic reactivity in various reactions, for example, carbene insertion reaction into X–H bonds (X = O, N, B, C, etc.) in their singlet state, − cyclization reactions with alkenes and alkynes, and nucleophilic addition to electrophiles such as carbonyl compounds . A series of organosilicon derivatives could be obtained starting with siloxycarbenes.…”