Lithium Bromide-Promoted Formal C(sp)-H Bond Insertion Reactions of β-Carbonyl Esters with Sulfoxonium Ylides to Synthesize 1,4-Dicarbonyl Compounds.

A LiBr-promoted formal C(sp)-H bond insertion reaction between β-carbonyl esters and sulfoxonium ylides is established. This practical reaction has a wide range of substrate scope for both β-carbonyl esters and sulfoxonium ylides to give a variety of 1,4-dicarbonyl compounds with 43-94% yields. The reaction features transition-metal-free reaction conditions and exclusive -alkylation chemselectivity. The use of bench-stable sulfoxonium ylides overcomes previous methods that require transition metal as catalysts and unstable diazo compounds or toxic haloketones as alkylation reagents.