Applications of high-potential quinones. Part VI. Stereoelectronic effects in the dehydrogenation of neoergosterols
Abstract
Neoergosterols undergo rapid hydrogen transfer with dichlorodicyanobenzoquinone at room temperature to give Δ14-derivatives in high yield. Further dehydrogenation also occurs in ring D, giving Δ14,16-neoergosterols. Stereoelectronic effects governing the rate and specificity of these oxidations are discussed. In the mass spectra of the Δ14,16-sterols, the preferred mode of side-chain fragmentation involves transfer of only one hydrogen atom from the nucleus.