Adolf von Baeyer worked on indigo…

.. specifically after that to come up with an aniline equivalent to the plant sourced dye.  In 1865 he started, by 1878 he had a first attempt using the chemical “isatin”, and in 1880 he made a 2nd successful attempt using the chemical “2-nitrobenzaldehdye”.

In 1883 he finally figured out the chemical structure of natural indigo, and gave up trying to duplicate it.  Instead, chemists like von Baeyer continued the work to create an entirely new structure that would look the same yet be able to be synthetically mass produced.

Karl Heumann, using “Badische anilin- and Soda Fabrik” or BASF, eventually figured it out.

(Photo: natural indigo today in India)