Arcutane diterpenoids are among the most structually complex natural products due to their congested tetracyclo[5.3.3.04,9.04,12]tridecane skeleton, many of the members of its family defying synthesis. A study published in 2016 succeeded in synthesizing one of the engimatic cage structures, namely atropurpuran. Their synthesis commenced from a simple aromatic aldehyde – and in just 5 steps – constucted the rightmost fragment of the natural compound with appropriately positioned functional groups. Deduce all the synthetic intermediates of the transformation lineated above.
For reference:
Gong, J., Chen, H., Liu, X.-Y., Wang, Z.-X., Nie, W., & Qin, Y. (2016).
“Total synthesis of atropurpuran.”
Nature Communications, 7, 12183.
doi:10.1038/ncomms12183