Copper(I)/N-Heterocyclic Carbene (NHC)-Catalyzed Addition of Terminal Alkynes to Trifluoromethyl Ketones for Use in Continuous Reactors

A copper(I)/N-heterocyclic carbene complex-catalyzed addition of terminal alkynes to trifluoromethyl ketones at low loading is described. The developed process functions well using a range of terminal alkynes but functions best when an aryl trifluoromethyl ketone is used. This substrate scope is well-suited for the production of active pharmaceutical ingredients (APIs) such as efavirenz. In this vein, we demonstrate that the described method can be translated into a flow process laying the framework for a completely continuous synthesis of efavirenz in the future.