Radical Addition of Arylboronic Acids to Various Olefins under Oxidative Conditions

Abstract

Arylboronic acids are shown to be valuable precursors for aryl radicals upon treatment with manganese triacetate. Under these oxidative conditions the intermediately generated aryl radicals undergo addition to olefins to give the arylhydroxylation products A in the presence of dioxygen. In the absence of dioxygen, for some olefins double olefin addition and subsequent homolytic aromatic substitution provide tetrahydronaphthaline derivatives B in moderate to good yields.

Manganese(IV)‐Mediated Hydroperoxyarylation of Alkenes with Aryl Hydrazines and Dioxygen from Air

“…In summary, we report a new carbooxygenation‐type version of the Meerwein arylation in which the introduction of oxygen has been achieved by using dioxygen from the air. In contrast to related reports,9, 11 the best results were obtained with α‐substituted acrylates. Importantly, the aryl hydrazine has to be added slowly to the reaction mixture to allow sufficient uptake of dioxygen from the air.…”

Practical C−H Functionalization of Quinones with Boronic Acids

“…21 Notably, arylboronic acids have recently been coupled to electron-deficient olefins in excess via a presumed radical mechanism with stoichiometric manganese(III) acetate (no quinone examples given). 22 Inspired by our recent discovery of the silver-catalyzed addition of arylboronic acids to protonated heterocycles, 23 and given the inherent reactivity of quinones with radicals, 1,2 it was reasoned that the same reactive intermediate generated from the boronic acid precursors could interact with other electrophiles such as quinones. In addition, the oxidizing conditions used to generate radicals from boronic acids would serve the dual role of reoxidizing the dihydroquinonesgenerated generated from the radical addition step.…”

Direct Alkylation of Heteroaryls Using Potassium Alkyl- and Alkoxymethyltrifluoroborates

“…Among the different metal oxidants that can be employed for this reaction, manganese acetate has proven to be efficient for the C-H arylation of olefins,10 arenes, and heteroarenes using arylboronic acids 11. However, the latter cases either used the substrate as a solvent or the reaction was performed with a 10-fold excess of the arene/heteroarene at 170 °C under microwave conditions.…”