抄録
In connection with studies aimed at the synthesis of biologically active normal steroids from etiojervanes, we prepared several 12,13-epoxyetiojervanes and examined acid and/or base epoxy cleavage reactions as well as photochemical transformations of the epoxy compounds. The epoxides, 11-oxygenated 17α-acetyl-12,13-epoxy- (20〜26) and 17-oxygenated 12,13-epoxy-etiojervanes (37〜42), were prepared according to the processes described in Charts 1〜3. The configuration of each epoxide was defined on the basis of the chemical and spectral evidence. Treatment of 17α-acetyl-12α,13α-epoxides (20, 20a, 21 and 26) with acid (BF_3) produced mixtures of several compounds, respectively, including interesting rearranged products, e.g., compounds (49 and 50) with bicyclo[3.3.1]nonane-2,9-dione and hydrooxepin moieties (Chart 4), while the 12α,13α-epoxides (20 and 23) on treatment with base (KOH) gave a 13α-pregnane derivative (52), but 11-unsubstituted 12α,13α-epoxide (26) and 12β,13β-epoxides (22 and 24) afforded no such rearranged products (Charts 5 and 6). Although no desirable rearranged products were obtained by acid treatment of 17-oxygenated 12α,13α-epoxides (37, 37a, 39 and 40), irradiation of epoxy-ketone (39) proceeded as expected to give an androstane derivative (67) (Charts 7 and 8).
