Organometallic‐Free Approches to the Direct Arylation of Benzoquinones and Naphthoquinones

Quinones represent a ubiquitous class of natural products, extensively distributed throughout nature. Within these organisms, they fulfil pivotal roles across a spectrum of metabolic processes essential to the organisms. Their privileged core structure is present in a variety of substances explored in medicinal chemistry. Modification of the central core of quinones could give rise to new substances with great potential as drug candidates. In this context, the introduction of an aryl or heteroaryl moiety on the quinone structure can be an important strategy for the development of new potentially bioactive compounds. In the present work, direct arylation methods of quinones reported in the literature are summarized, restricting the text to methods where organometallics are not used as catalysts, nor are organometallic species formed during the catalytic cycle. Radical arylation methods are presented where diazonium salts, hydrazines and arylboronic acids are used as aryl radicals’ sources, thermally and photochemically generated. Polar reactions are also presented, that is, through nucleophiles and electrophiles. In most reports, rich aromatics acts as nucleophiles against naphthoquinones, whose electrophilicity is increased by an Brönsted or Lewis acid. Quinones can be the starting materials or generated in situ from phenolic precursors. Arylquinones are present in many natural and synthetic molecules. They open up possibilities for application in various areas such as pigments and dyes, optical materials, sensors, pharmaceuticals, etc. Many of the methods to obtain them involve indirect arylation routes of precursors and a chemistry of oxidations, reductions, protection and deprotection of functional groups. In this review, direct arylation methods of quinones are compiled with a focus on processes where no C‐metal bonds are formed, i. e., organometallic‐free reactions.