Novel approach to the synthesis of the aromatase inhibitor 4-hydroxyandrost-4-ene-3,17-dione (4-OHA)

A straightforward synthesis of the title compound is achieved through a novel approach, comprising the oxidation of the easily available 5α-androst-3-en-17-one 1 in two sequential steps to yield the kinetic diosphenol 4, which gives the desired 4-OHA 5 by base-catalysed isomerization.