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Updated: Dec 27, 2025

A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products
Published on: September 9, 2016
Protecting-Group-Free Total Syntheses of (±)-Norascyronones A and B
Tingting Cao1, Lei Zhu2, Yu Lan2
1State Key Laboratory of Chemical Oncogenomics and Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School and Shenzhen Bay Laboratory, Shenzhen 518055, China.
Abstract:
Protecting-group-free total syntheses of natural products norascyronone A and norascyronone B were accomplished in eight steps from the commercially available starting material 1-bromo-4-methoxy-2-methylbenzene. The key step was a Mn/Cu-mediated oxidative cascade annulation reaction that formed the tetracyclic core of the target molecules bearing vicinal bridge-head all-carbon quaternary chiral centers. Our investigation indicated that the C5 stereogenic center of norascyronone C plays a critical role in the proposed biomimetic oxidative reaction for B-ring formation.
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