Rotation of Δ⁶-isoEquilin (6-Dehydroœstrone): a Correction

Abstract

IN 1940 we described the conversion of equilin, through 7-ketoœstrone, 7-hydroxyœstrone and 7-chloroœstrone, to its Δ⁶ double bond isomer¹. The specific rotation [α]_D²⁴ of this compound was then reported by us as +150° (in dioxane). Dr. St. Kaufmann, of Syntex, S.A., has kindly directed our attention to the widely divergent value (−127°) given by an otherwise apparently identical preparation obtained in that Laboratory from Δ⁴-androstenedione (cf. preceding communication by Rosenkranz et al.). A check determination now carried out on a small reference sample of Δ⁶-isoequilin still in our possession gave −120°, in fair agreement with the value of Rosenkranz et al. This preparation (m.p. 258–261°, corr.) did not depress the melting point of a specimen of 6-dehydroœstrone obtained from Dr. Kaufmann which in our hands melted at 257–260°; likewise, the melting point of a mixture of the respective 3-benzoates (m.p. 201°, 200°) was not depressed. It is clear, therefore, that the positive rotation figure originally recorded by us was in error, and that the two compounds in question are identical in every respect.