Cobalt(III) Porphyrin-Decorated Stereoregular Polyisocyanides Enable Highly Effective Cooperative Catalysis for Hydration of Alkynes

We report a facile strategy to boost cooperative catalysis for alkyne hydration using polymer-supported catalysts. In this work, cobalt(III) porphyrin is deliberately decorated onto stereoregular polyisocyanides to synthesize the functional polymer P1-Co. Owing to the preorganization of the rigid polymer skeleton, adjacent pendant cobalt(III) porphyrins are arranged in parallel with an average distance of ∼0.9 nm, in which both the nucleophilic and electrophilic substrates can be dual-activated. The catalytic effectivity is investigated via catalytic hydration of a series of terminal and internal alkynes. P1-Co exhibits high activity to afford the desired products in good to excellent conversions at low catalyst loadings (0.1 mol % for terminal alkynes and 0.3 mol % for internal alkynes). Conversely, the irregular polymeric analogs P2-Co and P3-Co as well as the small-molecule control C1-Co perform poorly due to the lack of a cooperative catalysis approach. To demonstrate its potential application in the pharmaceutical industry, the formal syntheses of four drugs involving hydration of alkynes as the key step are achieved in excellent yields.