 This phenomenon is demonstrated by observed selectivities in the rearrangements below.In the rearrangement on the left the thermodynamically unfavorable product is observed exclusively, while in the reaction on the right the product derived from the less stable radical intermediate is favored.Aubé takes advantage of this rearrangement as the key step in his synthesis of (+)-yohimbine, a natural medicine classified by the NIH as possibly effective in the treatment of erectile dysfunction and the sexual problems caused by selective serotonin reuptake inhibitors.