Furanosteroid studies. Improved synthesis of the A,B,C,E-ring core of viridin

The tetracyclic core skeleton of the furanosteroid viridin is prepared in nine steps from readily available materials. The key step in the synthesis is a facile acid-promoted cyclodehydration of an aryloxyketone to prepare the benzofuran moiety. From this intermediate, the known target skeleton is prepared in four steps. This new synthesis is a six-step improvement over the previously reported one.