Triethylamine → 20,20-Ethylenedioxy-2alpha-methyl-5alpha-pregnane-3,11-dione

Participants

Reaction Steps

A solution of chloroiridic acid (30 mg.) and trimethyl phosphite (4.5 ml.) in aqueous 90% isopropanol (60 ml.) was heated under reflux for 17 hr. The solution was then neutralised with triethylamine and 20,20-ethylenedioxy 2-hydroxymethylene-5α-pregnane-3,11-dione (2 g.) was added. The mixture was heated under reflux for 40 hr. then cooled and partitioned between water and methylene chloride. The organic layer was dried (MgSO4) and evaporated in vacuo. The residue (1.94 g.) was subjected to preparative t.l.c. giving two fractions. The less polar fraction (0.18 g.) was crystallised from methanol to give 20,20-ethylenedioxy-2α-methyl-5α-pregnane-3,11-dione (0.13 g.), m.p. 179°-180°, [α]D + 77.5°.

Provenance & Evidence