Construction of a BCDE Core of Furanosteroids Enabled by Nickel-Promoted Reductive Cyclization

We developed a new synthetic strategy for furanosteroids and constructed the BE ring system in one step by a Ni-catalyzed reductive cyclization cascade. The subsequent oxidative elaboration led to the efficient formation of a BCDE tetracyclic core embedded in these furanosteroids. Furthermore, a synthesis of the carbon skeleton of nodulisporiviridin C was achieved, as well, through this method.