Water → Pregn-5-en-20-yn-3-one, 17-hydroxy-, cyclic 1,2-ethanediyl acetal, (17alpha)-

Participants

Reaction Steps

Trimethylorthoformate (20 ml.) and p-TSA monohydrate (1.9 g.) is added to a slurry of ethisterone (I, 31.34 g.) in ethylene glycol (100 ml.) and methanol (200 ml.). The mixture is heated to 50° until the reaction is complete (about 5 hours) as measured by TLC. The mixture is cooled to 5° and water (200 ml.) containing sodium acetate (6.6 g.) is added. The resulting suspension is filtered to recover the solids which are dried at 50° under reduced pressure (20 mm) for 6 hours to give the title compound, m.p. 245°-250°; NMR (CDCl3) 0.87, 1.03, 2.57, 3.97 and 5.23δ.

Provenance & Evidence