From pregnancy urine: Hartmann, Locher, Helv. Chim. Acta 18, 160 (1935); Lieberman et al., J. Biol. Chem. 172, 263 (1948). Prepn from pregna-4,11-diene-3,20-dione: Shoppee, Reichstein, Helv. Chim. Acta 24, 356 (1941); by oxidation of allopregnan-3β-ol-20-one with chromium trioxide: Billeter, Miescher, ibid. 30, 1409 (1947); by hydrogenation of pregnenolone: Pappas, Nace, J. Am. Chem. Soc. 81, 4556 (1959); from funtumine: Janot et al., Bull. Soc. Chim. Fr. 1960, 1669.