Asymmetric Total Synthesis of (−)-Guignardones A and B
Zhiming Yan, Chunbo Zhao, Jianxian Gong, Zhen Yang
Abstract
The asymmetric total synthesis of (−)-guignardones A (2) and B (1) has been accomplished. The highly oxidized 6-oxabicyclo[3.2.1]octane core was constructed from d-quinic acid via substitution/desulfurization reaction with thiophenol to forge the bridged ring scaffold, and a Pummerer rearrangement and 1,4-addition/elimination sequence was employed to install the β-carbonyl group at the congested C-1 position. A late-stage Knoevenagel condensation–6π-electrocyclization and directed hydrogenation formed (−)-guignardone B (1), which was subjected to dehydration to furnish (−)-guignardone A (2).
Topics & Concepts
ChemistryTotal synthesisStereochemistryEnantioselective synthesisOrganic chemistryCatalysisCarbohydrate Chemistry and SynthesisPlant-derived Lignans Synthesis and BioactivityChemical synthesis and alkaloids