Efficient Access to Orthoquinols and Their [4 + 2] Cyclodimers via SIBX-Mediated Hydroxylative Phenol Dearomatization

SIBX, the nonexplosive formulation of the λ5-iodane 2-iodoxybenzioc acid (IBX), safely and efficiently mediates the
hydroxylative dearomatization of various 2-alkylphenols and
napthols into orthoquinols or their [4 + 2] cyclodimers.
Reactions are typically run at room temperature using SIBX
as a suspension in THF. Using these conditions, natural
products such as the cyclodimer of the terpene carvacrol and,
for the first time, the shikimate-derived (±)-grandifloracin
were prepared in one step from their respective phenolic
precursor.