The first orally active progestin, ethisterone (pregneninolone, 17α-ethynyltestosterone), the C17α ethynyl analogue of testosterone, was synthesized in 1938 from dehydroandrosterone by ethynylation, either before or after oxidation of the C3 hydroxyl group, followed by rearrangement of the C5(6) double bond to the C4(5) position. The synthesis was designed by chemists Hans Herloff Inhoffen, Willy Logemann, Walter Hohlweg and Arthur Serini at Schering AG in Berlin and was marketed in Germany in 1939 as "Proluton C" and by Schering in the U.S. in 1945 as "Pranone".