Hecogenin has been transformed into [11,11,12,12-2H4]progesterone via base-catalyzed isotope exchange with D2O (at C-11), carbenic decomposition of the 12-tosylhydrazone formed by the use of [N,N,N'-2H3]toluene-p-sulfonylhydrazine, and reduction with [2H2]diimide to give [11,11,12,12-2H4]tigogenin, followed by standard degradation of the spiroketal side chain and dehydrogenation in ring A.