Catalyst-dependent chemoselective formal insertion of diazo compounds into C-C or C-H bonds of 1,3-dicarbonyl compounds

A catalyst‐dependent chemoselective one‐carbon insertion of diazo compounds into the C−C or C−H bonds of 1,3‐dicarbonyl species is reported. In the presence of silver(I) triflate, diazo insertion into the C(=O)−C bond of the 1,3‐dicarbonyl substrate leads to a 1,4‐dicarbonyl product containing an all‐carbon α‐quaternary center. This reaction constitutes the first example of an insertion of diazo‐derived carbenoids into acyclic C−C bonds. When instead scandium(III) triflate was applied as the catalyst, the reaction pathway switched to formal C−H insertion, affording 2‐alkylated 1,3‐dicarbonyl products. Different reaction pathways are proposed to account for this powerful catalyst‐dependent chemoselectivity