25-Carboxylic acid derivatives in the vitamin D series, process for their production, intermediate products for these processes, pharmaceutical preparations containing these derivatives as well as their use for the production of pharmaceutical agents
New 25-carboxylic acid derivatives of general formula I, STR1 R19 and R19a each mean a hydrogen atom or together form an exocyclic methylene group, R21 and R21a independently of one another mean a hydrogen atom,