A STRIKING DIFFERENCE BETWEEN THE STEREOCHEMICAL COURSE OF THE PHOTOLYSIS OF 5-HYDROXY 6-OXO STEROIDS AND THEIR BICYCLIC ANALOGUES

Article abstract of DOI:10.1016/S0040-4039(01)80870-4

While 5α- and 5β-hydroxy 6-oxo steroids undergo stereospecific photoisomerization, their bicyclic analogues give identical product mixtures on photolysis.This is attributed to equilibration of the intermediate acyl alkyl diradials in the bicyclic case, which does not occur in the steroid case because of slowing of rotation about the C-9 - C-10 bond.