Sodium borohydride → Prednisolone 17,21-diacetate

Participants

Reaction Steps

To an ice cooled solution of intermediate 2 (2.22 g, 5.0 mmol) in tetrahydrofuran (15 ml) and MeOH (15 ml), sodium borohydride (221 mg, 5.84 mmol) is added in portions over a period of 2.5 hours. The reaction mixture is poured in 1 N HCl and ice (150 ml). The formed precipitate is extracted with AcOEt (3×100 ml), and the combined organic layers are dried over anhydrous Na2SO4 and concentrated. The crude material is crystallized from Ethyl acetate/petroleum ether. The residue from mother liquor is purified by flash chromatography on silica gel, in gradient elution from DCM to DCM/AcOEt 40:60 affording a second crop. The combined crops give the title the compound (1.85 g, 83% total yield).

Provenance & Evidence