When l-cholesteryl benzoate dibromide (I), m. 134°, was kept at 130-5° 5 min. the original [α]D -50° (C6H6) changed to 69°.Recrystallization from Me2CO gave pure benzoylcholesterol dibromide, m. 167°, [α]D 100° (C6H6).Keeping acetylcholesterol dichloride 1 hr. at 123-5° left the original [α]D -38° unchanged.Heating at 160-200° 1 hr. gave [α]D -11.2° (C6H6).Boiling cholesterol dibromide in C6H6 6 hrs. changed its rotation to 21°.Boiling acetylcholesterol dibromide in CCl4 9 hrs. reduced the rotation to 0°.By melting acetylcholesterol dibromide 20 min. at 117°, then dissolving it in glacial AcOH, and filtering off the unchanged substances, a d-dibromide, showing [α]D 43.8° (C6H6), may be precipitatedThe solution of the latter showed practically unchanged rotation at room temperature even after 60 hrs. (41.1°) but heating it at the b.p. of C6H6 caused rapid mutarotation: 23.7° after 2, 21.8° after 4, and 21.1° after 8 hrs.Further experiments were the following.(1) Acetylcholesterol dibromide (18 g.) was kept at 120° 20 min., dissolved in 650 ml. glacial AcOH, cooled to 15°, treated slowly within 6 hrs. with 15 ml. of a CrO3 solution (prepared by adding 27 g. CrO3, 30 ml. water, and 12.6 ml. H2SO4 to 126 ml. glacial AcOH), stirred 3-4 hrs., MeOH added, then 25 g. powd. Zn, the mixture kept at 35-40°, filtered, the solid washed with glacial AcOH and CCl4, the filtrate evaporated, the residue taken up in 200 ml. ether and 100 ml. water, the aqueous part shaken with 50 ml. ether, the Cr salts removed from the ether portions by washing with 100 ml. 10% H2SO4, the acids washed out with 10% NaOH solution, the neutral ether residue boiled in 20 ml. MeOH, the crystals of cholesterol acetate filtered off, and the filtrate boiled with a concentrated MeOH solution of H2NCONHNH2.HOAc for 90 min., filtered, washed with hot MeOH and C6H6, giving 0.72 g. acetyl-trans-dehydroandrosterone semicarbazone (II), m. 276°.(2) Cholesterol (615 g.) is boiled with 450 ml. Ac2O 2 hrs., the solution evaporated in vacuo, the residue dissolved in 2 l. CCl4, treated, under effective cooling, dropwise with 260 g. Br in CCl4 at such a rate as to keep the temperature below 5°, the solvent distilled down under a vacuum, the residue dried at 130°, cooled to 110°, 2000 ml. hot glacial AcOH added, the product washed with 500 ml. and once more with 1500 ml. in the oxidation apparatus, diluted with 28 l. glacial AcOH, treated with 1350 g. of the CrO3 solution as under (1), stirred 10 hrs. at 15°, and the procedure under (1) followed to obtain 38 g. II.(3) Acetylcholesterol dibromide (24.3 g.) is melted as above, then dissolved in 180 ml. lukewarm glacial AcOH, cooled, filtered, and the mother liquor oxidized as under (1) to obtain 0.65 g.II.(4) Cholesterol (2100 g.) is boiled with 1540 ml. Ac2O, and to the acetylcholesterol thus obtained is added 152 g. more from previous experiments, then 922 g. Br in 6.3 l. CCl4, the solvent evaporated under a vacuum, 460 g. l-cholesterol acetate dibromide from previous experiments added, and the mixture dissolved in 22 l. glacial AcOH; the 1088 g. l-dibromide which crystallizes is filtered, and the filtrate treated with a CrO3 solution prepared as under (1) from 4 kg.CrO3 yielding 123 g. II, m. 274°.(5) The dibromide is prepared from 0.3 g. trans-dehydroandrosterone acetate in 3 ml. CCl4 with 4 ml. CCl4 containing 4% Br, then evaporated under a vacuum, the residue dissolved in 30 ml. glacial AcOH, cooled to 15°, treated with 1.35 g. CrO3 solution as under (1), and set aside for 16 hrs. at room temperatureFurther treatment as under (1) gave 0.03 g. neutral residue which when boiled with H2NCONHNH2.HOAc in MeOH gave 0.04 g. II.8 references.
