The unexpected course of the reaction of steroid sapogenins with diacetoxyiodobenzene and BF3·Et2O in formic acid

The reaction of steroid sapogenins with diacetoxyiodobenzene and BF3·Et2O in formic acid produced a mixture of an equatorial 23-formyloxysapogenin, a 16β,23:23,26-diepoxy-22-one and a bisnorcholanic lactone.