Spiculoic acid A
Not just the total synthesis here, but also the assignment of the absolute configuration, Jack Baldwin et al. have used a really nice DA to assemble the 6,5 system. Starting back at the aldehyde, a Wittig olefination completed the tethered acyclic substrate for the DA, which spontaneously cyclised at 100 ÂºC. Nice way to construct two quaternary centres!
This completed the carbocyclic skeleton of the natural product, which required relatively few steps to deliver the desired compound.