Spirotryprostatin B is an indolic alkaloid found in the Aspergillus fumigatus fungus that belongs to a class of naturally occurring 2,5-diketopiperazines.  Spirotryprostatin B and several other indolic alkaloids (including Spirotryprostatin A, as well as other tryprostatins and cyclotryprostatins) have been found to have anti-mitotic properties, and as such they have become of great interest as anti-cancer drugs.  Because of this, the total syntheses of these compounds is a major pursuit of organic chemists, and a number of different syntheses have been published in the chemical literature.