ol0c00212_si_001.pdf (5.58 MB)
Protecting-Group-Free Total Syntheses of (±)-Norascyronones A and B
journal contribution
posted on 2020-02-25, 16:03 authored by Tingting Cao, Lei Zhu, Yu Lan, Jun Huang, Zhen YangProtecting-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.