16β-Alkoxy-17aα-hydroxy-D-homo-17-oxapregnan-20-ones: Preparation, Chemistry, and X-ray Crystallographic Analysis

Article abstract of DOI:10.1021/jo00317a031

Ozonolysis of certain Δ¹⁶-20-oxopregnanes in mixtures of dichloromethane-lower alkanol leads, after reductive workup with dimethyl sulfide, to novel derivatives of the 16β-alkoxy-17aα-hydroxy-D-homo-17-oxapregnane system.Under appropiate acidic conditions both the 16β-alkoxyl and 17aα-hydroxyl groups of these compounds can be replaced by alkoxyl groups derived from the solvent.The results of X-ray analysis of the 21-bromo derivative 4a (X=Br, R=Me) define the stereochemistry as 16β-methoxy-17aα-hydroxy.Comparison of the spectroscopic and physical properties of 4a (X=Br, R=Me) and rest of the compounds prepared strongly supports an analogous assignment.X-ray analysis also reveals an unprecedented (solid state) conformation for the C-17a side chain when compared to those of normal pregnan-20-ones.