Oxidative synthesis of ortho-quinones from hydroxy-PAHs by stabilized formulation of 2-iodoxybenzoic acid (SIBX)

Polycyclic aromatic phenols (PAPs or hydroxy-PAHs) are conveniently converted into their corresponding ortho-quinones using commercially available stabilized iodoxybenzoic acid (SIBX). SIBX provides a safer and commercially available alternative to IBX and displays the same selectivity with comparable or better yields in the oxidative dearomatization of phenols to ortho-quinone, including examples where forma-tion of para-quinones is feasible. This ortho-selectivity from all positions of a hydroxy-group allowed for simple synthesis of the prerequisite hydroxy-PAHs by either photochemical cyclization of stilbenes or Pt -catalyzed cycloisomerization. The later synthesis involved a four-step sequence where suitably substituted biphenyls were prepared by Suzuki-Miyaura cross-coupling, followed by the Corey-Fuchs protocol and cycloisomerization by a catalytic amount of PtCl2. 2-and 4-methylphenanthene were also prepared for the first time using this method.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

This study demonstrates the conversion of polycyclic aromatic phenols into their corresponding ortho-quinones using stabilized iodoxybenzoic acid. The results show that SIBX is a safer and commercially available alternative to IBX, with similar selectivity and better yields in the oxidative dearomatization reaction.