Chasing a Phantom by Total Synthesis: The Butylcycloheptylprodigiosin Case

The dispute as to whether “butylcycloheptylprodigiosin” is a natural product or solely a misassigned structure lasted for more than a decade. This open question has now been answered by the first total synthesis of this tripyrrole alkaloid (see picture), which makes explicit use of the peculiarities of its highly strained ortho-anellated nine-membered ring.