Hydrogen Peroxide → Androstenol

Beteiligte Stoffe

Reaktionsschritte

This synthesis is depicted in FIG. 1. To a 1M solution of lithium tris (1,2 dimethylpropyl) hydridoborate (c, commercially available from Aldrich, 2.5 ml, 2.5 mmol) at -55°, under N2, was added a solution of ketone 1 (500 mg, 1.84 mmol) in THF (7 ml) and the mixture was allowed to warm up to RT. After 3 h, the mixture was cooled to -55° and hydrolyzed by addition of water (1 ml), followed by EtOH (3 ml). The boranes were oxidized by adding to the mixture at -55° 10% aq. NaOH-solution (5 ml), followed by 30% aq. H2O2 -solution (3 ml), and stirring for 3 h at RT. Cyclohexane (100 ml) was added and the organic phase washed successively with water, sat. aq. NaHSO3 -solution and sat. aq. NaCl-solution; after drying (Na2SO4) and evaporation of the solvent, the residue was chromatographed on silica gel (60 g) with toluene/ethyl acetate 2:1. The axial alcohol 2 was eluted first (443 mg, 89%) and the second fraction contained the equatorial alcohol 3 (24 mg, 4.8%). An analytical sample of 2 was recrystallized from PE at 0°. M.p. 142°-144°, [a]D =+15° (C=1.33) ([2]: m.p. 143.5°-144°, [a]D16 =+13.9° (c=0.94)). - IR. (CDCl3): 3625m, 3450w, 1590w. - 1H-NMR. (360 Mhz): 0.77 (s, 3 H); 0.82 (s, 3 H); 4.03 (m, w1/2 ≈8, 1 H); 5.70 (m, 1 H); 5.83 (m, 1 H).

Herkunft & Nachweise