Catalytic intermolecular enal-alkyne [3 + 2] reductive cycloadditions.
A catalytic, intermolecular [3 + 2] reductive cycloaddition of enals and alkynes has been developed. The method provides a nickel-catalyzed strategy for combining two simple acyclic pi-systems into a five-membered ring product by effecting a net two-electron reduction of the starting materials mediated by triethylborane as the reducing agent. The use of a protic solvent is a key feature of the process.
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