Total synthesis of linoxepin facilitated by a Ni-catalyzed tandem reductive cyclization.

A nickel-catalyzed reductive cyclization was developed to construct the tricyclic core embedded in linoxepin, a cyclolignan with a unique benzoxepin ring. The generated diastereodivergent acetals could be converted to the common unsaturated lactone, thus allowing a racemic synthesis of this molecule after incorporation of the remaining aromatic ring. This strategy with a late-stage installation of the D-ring led to the facile production of several linoxepin analogs as well.