1235-13-8 19-Norspiroxenone 2',3'-alpha-Tetrahydrofuran-2'-spiro-17-(estr-4-en-3-one) BRN 1390059 L 586.153 Spiro(estr-4-ene-17,2'(3'H)-furan)-3-one, 4',5'-dihydro-, (17R)- Spiro(estr-4-ene-17,2'(3'H)-furan)-3-one, 4',5'-dihydro-, (17beta)-