Electrophilic Transition-Metal-Mediated Aromatization Reactions

Study of the reactivity of aromatic C-H bonds in the presence of transition metal compounds began in the 1960s despite the quite early discovery of Friedel-Crafts alkylation and acylation reactions with Lewis acid catalysts. In 1967, we reported Pd(II)-mediated coupling of arenes with olefins in acetic acid under reflux [1], The reaction involves the electrophilic substitution of aromatic C-H bonds by a Pd(II) species, as shown in Scheme 2, and this is one of the earliest examples of aromatic C-H bond activation by transition metal compounds. Al-... [Pg.194]

Can a transition-metal-free reaction even be labeled as C—H activation Some chemists have argued that true C—H activation requires oxidative addition or other metal C—H bond insertion step therefore, some radical-mediated C—H bond activation reactions might be better classified as homoly tic aromatic substitution (HAS), the radical variant of the better known electrophilic aromatic substitution (EAS). ... [Pg.22]

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