“…As early as 1961, a group of workers at Schering noted the rearrangement of a 17-ketosteroid, following hydrogen-atom abstraction from the C13 methyl group, to give a D-homo-18-norsteroid (Scheme 82). 221 In collaboration with Barton, they suggested that the expansion might occur via β-scission to give an acyl radical followed by recombination to give the larger ring. Following the exploitation of this type of rearrangement some 25 years later by the Beckwith and Dowd groups, [222][223][224] the discussion has expanded to encompass the question of rearrangement via a cyclopropyloxyl radical either as a true intermediate or a transition state (Scheme 83).…”