Benzene → Cholest-4-ene-3,6-dione

Participants

Reaction Steps

4-Cholesten-3,6-dione was prepared using 4-cholesten-3-one (Aldrich Co.) as a starting material by reference to the method of Hevl and Herr (F. W. Hevl and M. E. Herr, J. Am. Chem. Soc., 75: 1918, 1953) and that of Malhotra et al. (S. K. Malhotra, J. J. Hostynek and A. F. Lundin, J. Am. Chem. Soc., 90: 6565, 1968). Stated specifically, pyrrolidine (2.85 g) was added to a benzene solution (50 ml) of 4-cholesten-3-one (3.84 g) and the mixture was refluxed under heating for 24 hours. After cooling, the solvent and the excess pyrrolidine were distilled off under vacuum. Upon recrystallization from methanol, a colorless crystal of dienamine (4.16 g) was obtained. Cupric acetate (100 mg) was added to a benzene-methanol (500:10) solution of the dienamine (4.16 g) and air was introduced into the mixture for 24 hours. Then, a 2% aqueous solution (20 ml) of acetic acid was added and the mixture was stirred for 30 minutes and washed successively with water, a 1% sodium carbonate solution and a saturated saline solution. The resulting residue was dried, filtered and subjected to silica gel column chromatography (hexane:ethyl acetate=10:1) to yield a colorless crystal of 4-cholestene-3,6-dione (3.23 g).

Provenance & Evidence