%0 Journal Article %T Acid-catalyzed and photolytic reactivity of some unsaturated B-nor-5,10-secosteroidal ketones %A MIRA S. BJELAKOVIC %A VLADIMIR D. PAVLOVIC %A MILAN M. DABOVIC %A LJUBINKA B. LORENC %J Journal of the Serbian Chemical Society %D 2003 %I Serbian Chemical Society %X The acid-catalyzed reaction of (Z)- and (E)-B-nor-5,10-seco-ketones 2 and 3 resulted in an intramolecular cyclization to give the 5-hydroxy-A-nor-1b,5b-10(19)-methylidene derivative 8, the 5b-hydroxy-A-nor-1(10)-unsaturated compound 9 and the 5b,10a-dihydroxy-A-nor-product 10, from the (Z)-isomer and the 5-hydroxy-A-nor-1a,5b-10(19)-methylidene product 11, from the (E)-isomer. Upon UV-irradiation, the (Z)- and (E)-seco-ketones 2 and 3 underwent a reversible (Z)/(E) and (E)/(Z)-isomerization and in addition to a transannular photocyclization to afford the 10(19)-methylidene derivatives 8 and 11, respectively, while photolysis of the 10(19)-methylidene-B-nor-5,10-seco-ketone 4 gave the oxetane derivative 12. %K (Z)- and (E)-B-nor-5 %K 10-secosteroidal ketones %K 10(19)-methylidene-B-nor-5 %K 10-secosteroidal ketone %K acid-catalyzed reactions %K photolytic reactions %K mechanistic interpretation %U http://www.shd.org.yu/HtDocs/SHD/Vol68/No4-5/V68-No4_5-08.pdf