Catalytic Carbochlorocarbonylation of Unsaturated Hydrocarbons via C–COCl Bond Cleavage
There is an urgent requirement to construct C–C bonds, essential to the production and discovery of materials and bioactive compounds, with a focus on sustainability. Reactions that can form multiple C–C bonds in a single step in a modular fashion are rare. This task is made more demanding if it is to be achieved with complete atom economy, one aspect of sustainable synthesis. Previous work using transition metal catalysis has made initial progress in this area, activating C–C bonds within functional groups (e.g. C–CN bonds) or with directing groups. This activation allows for a formal addition of the C–C bond across unsaturated hydrocarbons.
To further develop this area of catalysis whilst exploring fundamental reactivity, we considered using readily available acid chlorides for the formal addition of C–COCl bonds across unsaturated hydrocarbons.1 The transformation was realized in both an inter- and an intramolecular setting, using strained alkenes and tethered alkynes, respectively. Notable features of the reaction include the high stereoselectivity, use of both aryl and alkenyl acid chlorides, good functional group tolerance, and the use of carboxylic acids as starting materials with in situ activation. Interestingly, the reaction also shows an example of temperature-dependent stereodivergence, which, together with plausible mechanistic pathways, was investigated by DFT calculations. Finally, the synthetic utility of the products was highlighted with the synthesis of tetrasubstituted cyclopentanes.
