Manganese-Catalyzed Ring Opening of Benzofurans and Its Application to Insertion of Heteroatoms into the C2-O Bond.

A new class of aromatic metamorphosis in which benzofurans are converted into diverse six-membered oxaheterocycles has been developed. This transformation is composed of two reactions in one pot: manganese-catalyzed arylative or alkylative ring-opening of benzofurans affording dianionic intermediates and subsequent trapping with multivalent heteroatom electrophiles. Various electrophiles containing silicon, boron, phosphorus, germanium, and titanium could be applied to this heteroatom insertion.