Reactions of Steroid Salts with Hexachlorocyclotriphosphazene

The sodium salts of the steroids desoxoestrone (VI), estrone (VII), β-estradiol (VIII), 17α-ethynylestradiol (IX), estradiol 3-methyl ether (XIV), and 1,4-dihydroestradiol 3-methyl ether (XV) were found to react with hexachlorocyclotriphosphazene (III) to yield species of the general formula N3P3C16(0R) (IV). The remaining halogen atoms were replaced by methylamine to yield hydrolytically stable derivatives of formula N3P3- (NHCH3)6(OR) (V). These are model compounds for the analogous steroid-substituted phosphazene linear high polymers. Aliphatic steroids such as cholesterol (X), dihydrocholesterol (XI), pregnenolone (XII), estradiol 3-methyl ether (XIV), or 1,4-dihydroestradiol 3-methyl ether (XV) underwent dehydration as well as substitution in contact with III. Mestranol (XVII) as its 17-sodium salt did not react rapidly with III, presumably for steric reasons. At elevated temperatures, estrone 3-methyl ether (XVI) interacted with III by a complex process that involved elimination of hydrogen chloride. All the chlorine atoms in III could be replaced by a reaction with the sodium aryloxide salt of estrone (VII). The replacement followed a nongeminal pathway. The significance of these results for the synthesis of the related high polymers is discussed.