A Selective C–C Bond Cleavage Strategy Promoted by Visible Light

Abstract

A new visible-light-promoted reaction between aryldiazoacetates and 1,3-diketones allows good yields and selectivities for C–C bond insertions, leading to the corresponding 1,4-dicarbonyl compounds. This transformation is straightforward and highly practical. It tolerates air and moisture and does not require the use of any metals. Mechanistic investigations support the involvement of a key cyclopropanol intermediate derived from an intramolecular rearrangement.

A Computational Study on the Photochemical O–H Functionalization of Alcohols with Diazoacetates

“…These transformations are considered to feature a key free singlet carbene intermediate that undergoes rapid downstream reactions, e.g. in cycloaddition, − ylide formation, , multicomponent, X–H, ,− C–H functionalization reactions, and others . Moreover, such photochemical carbene transfer opens up distinct reaction pathways via carbene intermediates that are inaccessible via classic metal-catalyzed carbene transfer reactions, as shown in multicomponent or C–C cleavage reactions.…”

Visible-Light-Mediated Formal Carbene Insertion Reaction: Enantioselective Synthesis of 1,4-Dicarbonyl Compounds Containing All-Carbon Quaternary Stereocenter

“…Subsequently, Koenigs et al disclosed an auxiliary photocarbene transfer reaction for diastereoselective synthesis of tetrahydrofurans. Very recently, Jurberg reported a visible-light-induced transformation of 1,3-diketones with aryl diazoesters into 1,4-diketones. Although a formal photochemical carbene transfer reaction of 1,3-diketones with aryl diazoesters has been utilized to synthesize 1,4-dicarbonyl compounds, the enantioselective method has not been realized.…”

Enabling Cyclopropanation Reactions of Imidazole Heterocycles via Chemoselective Photochemical Carbene Transfer Reactions of NHC-Boranes

“…Herein we report on our studies on the reaction of NHC-BH 3 with diazo compounds under visible-light irradiation (Scheme b). , We describe the application of this strategy in the chemoselective cyclopropanation of the imidazolium backbone NHC-borane complexes and thus showcase the cyclopropanation of imidazole heterocycles in carbene transfer reactions. We further engage in the dual functionalization of NHC-boranes via cyclopropanation and B–H insertion reactions and selective B–H insertion reactions via blocking of cyclopropanation sites.…”