Mass spectrometry of 16,16'-O-Permethylated 17-Ketosteroids

Using methylsulphinyl carbanion as base. methylation of 17-ketosteroids with methyl iodide not only converts hydroxy into methoxy groups, but also replaces both C-16 hydrogen atoms by methyl groups. These permethyl derivatives are very stable, have excellent properties for gas chromatographic separation and fragment characteristically upor electron impact. The mass spectra of a number of these derivatives are discussed.