The asymmetric total
synthesis of (−)-viridin and (−)-viridiol,
antifungal metabolites, was achieved in 17 and 18 steps from a commercially
available starting material. An intramolecular [3+2] cycloaddition
was applied to an easily available
l
-ribose
derivative in order to construct the highly substituted D ring containing
the key chiral cis-triol fragment. Co-catalyzed metal-hydride
H atom transfer (MHAT) radical cyclization was utilized to form the
C-ring and the all-carbon quaternary center at C-10. This convergent
strategy provides a scalable approach to prepare viridin and viridiol
for biological studies.
The first total synthesis of (-)-xestosaprol N and O is described. This synthetic work features a convergent strategy: (1) a Pd-catalyzed arylation followed by cyclization to build a naphthalene fragment (ring C, D); (2) utilization of (-)-quinic acid to construct the chiral hydroxyl group at C-2; (3) a substrate controlled intramolecular Heck reaction to construct a quaternary carbon center (ring B); (4) introduction of a hypotaurine moiety at a late stage to furnish the E ring.
Treatment with "TTK" improved the survival rates of patients with liver failure due to chronic hepatitis B. Additionally, liver tissue was regenerated and liver function was restored.
The asymmetric total synthesis of (+)-nodulisporiviridin E was achieved in 16 steps. This convergent approach provides an advanced Michael acceptor, which might facilitate the preparation of various analogues and derivatives for biological studies.
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