Capillary gas chromatographic behaviour of tert.-hydroxylated steroids by trialkylsilylation.
Capillary gas chromatographic behaviour was studied for a variety of structurally different bile acids and sterols having one to two tert.-hydroxy groups, together with several sec.-hydroxy groups, at positions C-3, -5, -7, -12, -14, -17, -20, -24, and/or -25. The tert.-hydroxylated steroids were subjected to trimethylsilylation with hexamethyldisilazane/trimethylchlorosilane /pyridine and N,O-bis(trimethylsilyl)acetamide/N-trimethylsilylimidazole/trimethylchlorosilane, and dimethylethylsilylation with N,N,-dimethylethylsilylimidazole. The methylene unit values of the resulting trialkylsilylation products were used for determining their structures of partially and/or fully derivatised ethers. The reactivity of the trialkylsilylation of tert.-hydroxy groups was found to be significantly dependent not only on the derivatisation reagents and conditions used, but also on the position and steric factor of the tert.-hydroxy groups. The following general order of the decreasing reactivity of tert.-hydroxy groups in steroids by trialkylsilyl etherification was observed: 25>20, 24>5beta>17alpha>>14alpha.
Iida
T
T
Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajousui, Tokyo, Japan. takaiida@chs.nihon-u.ac.jp
Hikosaka
M
M
Goto
J
J
Nambara
T
T
D002849:Chromatography, Gas / Q000379:methods*; D006900:Hydroxylation; D015394:Molecular Structure; D012794:Sialic Acids / Q000737:chemistry*; D013256:Steroids / Q000737:chemistry*
D012794:Sialic Acids; D013256:Steroids