AbstractIn analogy to the previously described photochemical isomerisation of 3,20‐diethylenedioxy‐11‐oxo‐5 α‐pregnane (I → II) the UV.‐irradiation of the Δ5‐ and 5β‐11‐oxo‐steroids III and XXII gives rise to the 11 α‐hydroxy‐11, 19‐cyclo derivatives IV and XXIII, respectively. The observed yields of these tertiary cyclobutanol products decrease in the order II > IV > XXIII. The possible significance of these structure‐dependent rate differences is discussed.
AbstractIn analogy to the previously described photochemical isomerisation of 3,20‐diethylenedioxy‐11‐oxo‐5 α‐pregnane (I → II) the UV.‐irradiation of the Δ5‐ and 5β‐11‐oxo‐steroids III and XXII gives rise to the 11 α‐hydroxy‐11, 19‐cyclo derivatives IV and XXIII, respectively. The observed yields of these tertiary cyclobutanol products decrease in the order II > IV > XXIII. The possible significance of these structure‐dependent rate differences is discussed.