25122-57-0Relevant articles and documents
Investigations on the polymorphism and pseudopolymorphism of clobetasone butyrate
Naether, Christian,Jess, Inke
, p. 553 - 566 (2011)
Clobetasone butyrate was investigated for polymorphism and pseudopolymorphism. Solvent mediated conversion experiments reveal that the commercially available form I represent the thermodynamically most stable form at room temperature and DSC measurements shows that it should also be the most stable form until melting. Form I crystallizes in space group P2 12121 with three crystallographically independent molecules of similar conformation. From methanol an additional pseudo polymorphic form was discovered. In the crystal structure (space group P212121) the solvent molecules are connected to the clobetasone butyrate molecules by O-H···O hydrogen bonding. Investigations of the solvate using thermogravimetry, differential thermoanalysis as well as differential scanning calorimetry proves, that on solvent removal an amorphous form is obtained that crystallizes into form I on further heating.
Process for the preparation of 21-halogeno-21-desoxy-17α-acyloxy-20-keto-pregnenes
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, (2008/06/13)
21-Halogeno-17α-acyloxy-20-keto-4-pregnenes having physiological properties are prepared by the reaction of a 17α,21-dihydroxy-20-keto-4-pregnene 17α,21-orthoester with a halide reagent selected from the group consisting of triarylsilyl halides and tri-lower alkylsilyl halides in an organic solvent, said halide being chloride or bromide. Preferred reagents are tri-lower alkylsilyl halides, particularly trimethylsilyl chloride.
