Syntheses of Quaternary Carboxylic Acid Derivatives via a Photo-Wolff Rearrangement/Pd Catalysis Sequence

Expedient synthesis of two types of quaternary carboxylic acid derivatives from α-carbonyl diazo substrates was established via a sequential photo-Wolff rearrangement/Pd-catalyzed difunctionalization of ketene. Allyl oxyphthalimide was used for the first time as a bifunctional allylating reagent to provide access to quaternary redox-active esters. A three-component reaction with allyl chloride as an allylating reagent in the presence of an external nucleophile was also accomplished to afford quaternary esters.