You mean whether it is biologically available? I guess, the synthesis has been out there since the 1940s, and other procedures has been found in the 1970s: http

You mean whether it is biologically available? I guess, the synthesis has been out there since the 1940s, and other procedures has been found in the 1970s: https://community.dur.ac.uk/i.r.baxendale/papers/Tet2016.72.1645.pdf https://community.dur.ac.uk/i.r.baxendale/papers/Tet2016.72.... Because these procedures are still in use, my hunch is that they are in use in vain.