A biosynthetic pathway was recently proposed for the polycyclic, cytotoxic compound aspernomine, isolated from the fungus Aspergillus nomius (J. Am. Chem. Soc. 2012, 134, 8078–8081):
(d) Consider the six-carbon acyclic substituent bound to one of the bridgehead carbons. What is its relationship (axial or equatorial) to each of the chairs?