Hydrochloric Acid → 3alpha,7beta-Ditetrahydropyranyloxy-5beta-cholan-24-ol

Beteiligte Stoffe

Reaktionsschritte

To a solution of compound (2) (9.80 g; 17.48 mmoles) in anhydrous tetrahydrofuran (250 ml), at -70° C. under magnetic stirring and nitrogen atmosphere, N-methylmorpholine (1.76 g; 17.48 mmoles) and isobutyl chloroformate (2.87 g; 21.0 mmoles) were added. The reaction mixture was left to react for 30 min., the separated solid was then removed by filtration and the filtrate was added to a sodium borohydride solution (1.65 g; 43.6 mmoles) in water (10 ml) kept at -10° C. under magnetic stirring at room temperature, in about 30 min., and the resulting mixture was left to react overnight at r.t. Thereafter the reaction mixture was diluted with ethyl acetate (20 ml) and water (80 ml), acidified with 5% hydrochloric acid and extracted with ethyl acetate (3×50 ml). The combined organic phases were washed with saturated water (1×50 ml), dried over sodium sulfate and concentrated under vacuum. A residue (9.40 g) was obtained which was subjected to flash chromatography on SiO2 (φ=5.5 cm, h=20 cm): eluting with 99/1 chloroform/methanol, 6.8 g of compound (3) were obtained, (71%); 1H-NMR (CDCl3)δ 0,7 (s, 3H, 18-CH3); 0,9-1,0 (m, 6H, 19-CH3, 21-CH3); 2,15-2,3 (s, 1H, --OH); 3,3-4,1 (m, 8H, 3-CH-, 24-CH2 -, 2x-O-CH2 -); 4,4-4,75 (m, 2H, 2x-O-CH-O-).

Herkunft & Nachweise