Synonyms: Pregn-4-ene-3,20-dione,16a,17-dihydroxy-6a-methyl-, cyclic acetal with acetone(7CI,8CI); Progesterone, 16a,17-dihydroxy-6a-methyl-, cyclic 16,17-acetal with acetone (6CI);2H-Naphth[2',1':4,5]indeno[1,2-d][1,3]dioxole, pregn-4-ene-3,20-dione deriv.;16a,17-Isopropylidenedioxy-6a-methylprogesterone; NSC 56948