Acid-catalyzed and photolytic reactivity of some unsaturated B-nor-5, 10-secosteroidal ketones

Abstract

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-1β,5β-10(19)-methylidene derivative 8, the 5β-hydroxy-A-nor-1(10)-unsaturated compound 9 and the 5β,10β-dihydroxy A-nor-product 10, from the (Z)-isomer and the 5-hydroxy-A-nor-1β,5β-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.

Kiselo-katalizovana reakcija (Z)- i (E)-B-nor-5,10-seko-ketona 2 i 3 rezultuje u intramolekulskoj ciklizaciji dajući 5-hidroksi-A-nor-1β,5β-10(19)-metilidenski derivat 8, 5β-hidroksi A-nor-1(10)-nezasićeno jedinjenje 9 i 5β,10β-dihidroksi-A-nor-proizvod 10, iz Z-izomera, i 5-hidroksi-A-nor-1β,5β-10(19)-metilidenski proizvod 11, iz E-izomera. (Z)- i (E)-Seko- ketoni 2 i 3 UV-ozračivanjem podležu reverzibilnoj (Z)/(E) odnosno (E)/(Z) izomerizaciji, kao i transanularnoj fotociklizaciji dajući 10(19)-metilidenske derivate 8 odnosno 11, dok se fotolizom 10(19)-metilidenskog-5,10-seko-ketona 4 gradi oksetanski derivat 12.