Neue Substitutionsreaktionen bei Steroiden

Summary The intramolecular substitution of the angular methyl groups in steroids by attack of O-radicals derived from 6-, 11, and 20-alcohols is discussed. Irrespective of their genesis, these radicals abstract a hydrogen atom from one of the said methyl groups, suitably oriented in-position. The C-radicals thus formed give different products depending on the neighbouring groups.It is shown that 20-hydroxy-18-C-radicals combine with iodine atoms, to give 18-iodides which can befurther substituted through radicals to give potential 18-oxo-compounds in high yield. In the case of 20-cyanohydrines, the intramolecular reaction of the 18-C-radical with the cyano groups gives rise to the new 18-cyano-20-oxo-steroids.With 6- and 11-O-radicalssingle substitution in 19-position predominates, since the steric arrangement of the primary product favours the intramolecular ether formation over a second substitution reaction.A general reaction scheme for these transformations is proposed.

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Vorgetragen vonCh. Meystre am 23. 9. 61 anlässlich der Sommerversammlung der Schweiz. Chem. Gesellschaft in Biel (vgl. Chimia15, (1961), im Druck).

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Über Steroide 180. Mitteilung. 179. Mitt. vgl.A. Wettstein, Exper.17, 329 (1961).