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Updated: May 13, 2025

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products
Published on: September 9, 2016
Total synthesis of (-)-griseocazine D2 and D3
Subhasish Pradhan1, Rajesh Viswanathan1
1Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, India. rajesh@labs.iisertirupati.ac.in.
Abstract:
The first stereoselective total synthesis of (-)-griseocazine D2 and D3 is reported. (-)-Griseocazine D2 and D3 are multiprenylated pyrroloindoline-DKP alkaloids biogenetically related to several bioactive natural products. These alkaloids are neuroprotective agents as recently shown through a glutamate-induced excitotoxicity model by Pei-Yuan Qian et al. Structural challenges include a 7-annulated-ring system with 6 stereocenters among which two are all-carbon quaternary centers. Our concise and enantiospecific route accesses (-)-griseocazine D2 and D3 in four steps and 24% and 32% overall yields, respectively. L-Tryptophan is used as a common precursor for the regio- and stereoselective C3-isoprenylation step to afford complete diastereocontrol across the pyrroloindolines.
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