Geminal Difunctionalization of Vinylarenes: Concise Synthesis of 1,3-Dioxolan-4-ones

We report a straightforward method for the synthesis of five-membered 1,3-dioxolan-4-ones by an unprecedented oxidative alkene geminal difunctionalization strategy using alpha-hydroxy carboxylic acids. Under the geminal oxidative addition conditions, various substituted alpha-hydroxy carboxylic acids and styrenes containing a variety of substituents, including beta-substituted styrenes, were effectively coupled regioselectively (anti-Markovnikov) with an isobutyl-substituted chiral alpha-hydroxy carboxylic acid, providing an annulation with excellent dia--stereoselectivity. An aryl migration in the semipinacol rearrangement leading to geminal oxidative addition of the alpha-hydroxy carboxylic acids was confirmed by deuterium-labelling and control studies.