11-Step Total Synthesis of Araiosamines

A concise route to
a small family of exotic marine alkaloids known as the araiosamines
has been developed, and their absolute configuration has been assigned.
The dense array of functionality, high polarity, and rich stereochemistry
coupled with equilibrating topologies present an unusual challenge
for chemical synthesis and an opportunity for innovation. Key steps
involve the use of a new reagent for guanidine installation, a remarkably
selective C–H functionalization, and a surprisingly simple
final step that intersects a presumed biosynthetic intermediate. Synthetic
araiosamines were shown to exhibit potency against Gram-positive and
-negative bacteria despite a contrary report of no activity.