Cholest-5-ene-1,7-dione, a new polyfunctional steroid, gave l-hydroxy-l,5«-cyclocholestan-7-one (6) on dissolving metal reduction. Acidand base-catalyzed isomerizations of 6 were studied and the results compared with corresponding reactions of the parent cyclopropanol la. The chief rearrangement products from 6 were the cis and trans 1,7-diketo steroids 10 and 11 and the ring-A spiro epimers 12 and 13. Surprisingly, no B-norsteroid products were obtained despite the isolation of an isomer of 6, 7-hydroxy-5,7d-cyclocholestan-l-one ( 14), from the base-induced reaction of 6. Ring-cleavage reactions of reduced derivatives of 6 and 14 were also examined.
A facile preparation of 6,9,9-trimethylbicyclo[5.3.0]deca-l,6-dien-3-0ne (6) from 2,5,5-trimethylcyclohexane-1,3-dione is described. Enolate reactions of 6 do not yield norcaradiene products, but proceed in the conventional manner (e.g., a-methylation and 0-silylation). Nucleophilic addition reactions at the carbonyl function, and epoxidation of the y,6 double bond are also observed. Under a variety of conditions, singlet oxygen reacts with the diene moiety in 6 to give both endoperoxide (13) and ene reaction (14) products in roughly equal amounts. The endoperoxide rearranges to cyclic hemiketal (15) on treatment with base.
Aus dem 1α‐Hydroxy‐cholest‐5‐en (I) erhält man nach Oxidation zu (II) bei weiterer Oxidation das Keton (III), das mit Li/Ammoniak zum Alkohol (IV) addiert.
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