Total Synthesis and Structural Revision of (±)-Mauritamide B

Area of Science:

• Organic Chemistry
• Marine Natural Products Chemistry
• Synthetic Chemistry

Background:

• Mauritamide B (1a) is a unique taurine-connected cyclic guanidino-bromopyrrole alkaloid.
• Marine sponges, such as *Agelas linnaei*, are sources of complex bioactive compounds.
• The total synthesis of taurine-connected guanidino-bromopyrrole alkaloids remains an underexplored area.

Purpose of the Study:

• To achieve the first total synthesis of mauritamide B.
• To investigate the structure of mauritamide B through synthetic and analytical methods.
• To provide a synthetic route for related alkaloids.

Main Methods:

• Oxidation of 2-aminoimidazole of dihydro-sventrin (10) using activated carbon and air in the presence of taurine.
• Synthesis of the precursor 4-(3-aminopropyl)-2-aminoimidazole (22) via an original route.
• Detailed NMR analysis, including 1H-15N HSQC, of the synthesized compound.

Main Results:

• Successful total synthesis of (±)-mauritamide B (1b).
• The obtained NMR data initially agreed with the reported data for mauritamide B (1a).
• In-depth NMR analysis indicated a potential need for structural revision of mauritamide B.

Conclusions:

• The study presents the first total synthesis of a taurine-connected cyclic guanidino-bromopyrrole alkaloid.
• The synthetic efforts and subsequent structural analysis highlight potential inaccuracies in the previously reported structure of mauritamide B.
• This work lays the foundation for further synthetic exploration of this alkaloid class and clarifies structural assignments.