A Very Short Synthesis of 3-Methoxyestra-1,3,5,8,14-pentaen-17-one.

3-Methoxyestra-1,3,5,8,14-pentaen-17-one (4) was prepared from 6-methoxy-1-tetralone (8) by an efficient two-pot procedure in which the D ring was generated by the Lewis acid catalysed reaction of 1,2-bis(trimethylsiloxy)cyclobutene (5) with an appropriate ketal (10). Keywords: steroid, estrone, annellation.