General Discussion

Yam and soy steroids had to be subjected to ingenious chemical modifications to have the same molecular structure as the natural hormones; for commercial success, they needed to be available in quantity, and isolated fairly efficiently, both of which required considerable ingenuity, as well as considerable patience with trial-and-error results.

Chemically, there is no distinction between these particular synthetic hormones and those from natural sources (not true of all steroids in use, by any means).

For the synthesis from steroids found in yams, read up on Russel Marker: https://www.acs.org/education/whatischemistry/landmarks/progesteronesynthesis.html

For soy steroids, see the work of Percy Julian: https://en.wikipedia.org/wiki/Percy_Lavon_Julian

PBS has shown docs on both men and their work. They were working on similar projects at about the same time, but that often happens in science, as new discoveries lead to whole new fields of study, which lead to new discoveries. "Success" wasn't a one-time thing either, so "who was first" is kind of a fuzzy question -- or at least a question with a fuzzy answer.