The titled compound 12 was obtained through seven steps using the comp
ound 3 as starting material. Hydrogenated compound 4 obtained from 8 w
as cyclized with H2SO4 to the compound 6, hydrogenation of which gave
a mixture of the compound 7 and 8. The compound 8 was also secured dir
ectly by reduction of 6 with Li and liq. NH3. Deprotection of the comp
ound 8 by HCl gave the compound 9 which was oxidized to the compound 1
0. Introducing the methylene group by dimethyl oxosulfonium methylide
at 17-ketone in the compound 10 gave the epoxide 11 which was cleavage
d to the titled compound 12 by NaCN.