Bismuth(III)-Catalyzed Hydration of Terminal Alkynes: Sustainable Synthesis of Methyl Ketones in Batch and Flow

Environmentally benign synthesis of methyl ketones is demonstrated via unprecedented bismuth(III)-catalyzed activation and Markovnikov-type hydration of terminal acetylenes. Besides a batch process operating under reasonably mild conditions, a chemically intensified high-temperature continuous-flow methodology has also been developed using a coil reactor. The preparative capabilities of the flow process were demonstrated with multigram-scale alkyne hydrations. The methods presented rely on readily available bismuth(III) salts as green catalysts and exhibit less environmental concerns than earlier methods.