The dehydrogenation of lanosterol derivatives by 2,3-dichloro-5,6-dicyanobenzoquinone

The dehydrogenation of 3β-acetoxylanost-8-ene (1a) by 2,3-dichloro-5,6-dicyanobenzoquinone to give, after hydrolysis, 3β-hydroxylanosta-7,9(11)-diene (2b), 3-hydroxy-19(10→5)abeo-4,5-secolanosta-4(30),5,7,9,11-pentaene (3a), and 19(10→5)abeo-4,5-secolanosta-5,7,9,11-tetraen-3-one (4) is described. Similarly 3β-hydroxylanost-8-ene (1b) is also dehydrogenated to a mixture of (2b) and (4).