Arylative Allenol Cyclization via Sequential One-pot Enzyme & Palladium Catalysis

The one-pot combination of halogenation biocatalysis and Suzuki-type cross coupling enables the direct arylative cyclization of allenic alcohols with boronic acids. This modular approach to unsaturated five-membered O-heterocycles proceeds in an aqueous emulsion with air as terminal oxidant. Here, the enzymatic oxidative activation of simple halide salts acts as traceless ring-closure-inducing event to trigger the subsequent C−C coupling. With the original protocol merging soluble proteins and a homogeneous SPhos-based palladium catalyst as a template, a novel heterogeneous nanobiohybrid was developed. Consisting of an oxidase matrix hosting small spherical palladium nanoparticles, this enzyme-metal hybrid exhibits catalytic competence for both the biocyclization as well as the C−C bond-forming cross coupling, underlining the potential of this new techniques for streamlining chemoenzymatic approaches.