Abstract: A process for the preparation of 16,17 acetals of pregnane derivatives by trans-ketalization of 16,17-acetonides is described.In the instance of the preparation of 16.alpha.,17.alpha.-butylidenedioxy-11.beta.,21-dihydroxypregna-1,4-diene- 3,20-dione, a compound having useful therapeutic properties, known also as budesonide, it is possible to obtain the more active epimer with high selectivity and remarkable economic advantages in comparison with the known methods.New 16,17 acetals of pregnane derivatives, which can be prepared by the method of the invention, are also described.

Abstract: Novel 6.alpha.-fluoro-9.alpha.-chloro-16.beta.-methyl-prednisolone 17, 21-diesters, and a method for their preparation, are described. The novel products are particularly valuable as anti-inflammatory agents.

Abstract: The present application relates to novel 6.alpha.-fluoro prednisolone 17, 21-diesters, to pharmaceutical compositions comprising such diesters, and to methods of treating inflammatory conditions with such diesters.

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.