Abstract: The invention relates to 3-acetoxy-9.beta.,11.beta.,-epoxy-pregna-1,3,5-trienes and the corresponding 3,5-dienes having the general formula 1, in which on the 1,2-position a double bond may be present and in which R.sub.3 is a hydrogen or halogen atom or a hyroxy-, acyloxy-, aroyloxy or sulphonyloxygroup; R.sub.1 and/or R.sub.2 are a hydrogen atom or a hydroxy-, aroyloxy-, acyloxy- or alkylgroup containing 1-6 carbon atoms, or in which R.sub.1 and R.sub.2 form together a 16,17-isopropylidene-dioxy group, a process for the preparation of this compounds by reacting the corresponding .DELTA..sup.1,4 -3-keto-pregnadienes or .DELTA..sup.4 -3-keto-pregnenes with isopropenylacetate and a process for their direct conversion into the corresponding 6.alpha.-halogen-substituted-pregna-1,4-diene-3-ones and pregn-4-ene-3-ones with the general formula 2 by reacting them with a positive-halogen producing agent.