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.

Blue light irradiation of aryldiazoacetates leads to the formation of free carbenes, which can react with carbazoles, pyrazoles and 1,2,3‐triazoles to afford the corresponding N−H inserted products. These reactions are performed under air and at room temperature, allowing the mild preparation of a variety of motifs found in biologically relevant targets.

Two new visible-light-mediated strategies are described starting from aryldiazoacetates. The first approach describes their reaction with azides to afford the corresponding imines, and then reaction with aryldiazoketones produces alkyl 2carboxylate-2,3,3-trisubstituted β-lactams. The second approach describes the reaction with sulfoxides to afford the corresponding sulfoxonium ylides, followed by reaction with aryldiazoketones to produce 5-alkoxy-2,2,4-trisubstituted furan-3(2H)-ones. These protocols take advantage of the photolysis of aryldiazoacetates and the photochemically promoted Wolff rearrangement of aryldiazoketones.

A general platform for the conversion of isoxazol‐5‐ones to 3,5‐disubstituted isoxazoles has been developed via a two‐step strategy. The first step leads to the formation of 5‐(pseudo)halogenated isoxazoles, while in the second, a variety of heteroalkyl‐, heteroaryl‐, alkyl‐, alkenyl‐, alkynyl‐ and aryl‐chains can be installed via nucleophilic substitutions or palladium catalyzed cross‐coupling reactions.

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