Catalytic Carbochlorocarbonylation of Unsaturated Hydrocarbons via C-COCl Bond Cleavage*

Abstract

Here we report a palladium-catalysed difunctionalisation of unsaturated C-C bonds with acid chlorides. Formally, the C-COCl bond of an acid chloride is cleaved and added, with complete atom economy, across either strained alkenes or a tethered alkyne to generate new acid chlorides. The transformation does not require exogenous carbon monoxide, operates under mild conditions, shows a good functional group tolerance, and gives the isolated products with excellent stereoselectivity. The intermolecular reaction tolerates both aryl- and alkenyl-substituted acid chlorides and is successful when carboxylic acids are transformed to the acid chloride in situ. The reaction also shows an example of temperature-dependent stereodivergence which, together with plausible mechanistic pathways, is investigated by DFT calculations. Moreover, we show that benzofurans can be formed in an intramolecular variant of the reaction. Finally, derivatisation of the products from the intermolecular reaction provides a highly stereoselective approach for the synthesis of tetrasubstituted cyclopentanes.

Keywords: Acid chlorides; CO-free; Carbonylation; Difunctionalisation; Palladium.