Water → 1 Alpha,25-dihydroxycholesterol

Participants

Reaction Steps

To a cooled, stirred solution of 4.05 g (10.1 mmol) of cholesta-5,24-diene-1α,3β-diol in 53 ml of tetrahydrofuran in an ice bath was added 33 ml of water followed by 4.0 g (12.5 mmol) of mercuric acetate. The bath was removed. After 2 hr., the reaction was still incomplete (tlc) so 0.4 g (1.3 mmol) of mercuric acetate was added. After 4 hr., 800 mg (21.1 mol) of sodium borohydride was added, followed after 30 min. by 190 ml of saturated brine and extraction of the resulting suspension with 5×50 ml of methylene chloride. The organic phases were backwashed with 20 ml of brine, dried (Na2SO4), filtered and evaporated. The residue was chromatographed on 400 g of silica gel. Elution with 5% methanol--chloroform and combination of fractions according to tlc (10% methanol--chloroform) afforded 3.60 g (85%) of 1α,25-dihydroxycholesterol, mp 165°- 167° C.

Provenance & Evidence