Twofold Electrochemical Amination of Naphthalene and Related Arenes

Abstract

The twofold electrochemical amination reaction of polycyclic arenes, such as naphthalene (4), via Zincke intermediates is demonstrated for the first time. The installation of nitrogen functionalities occurs regioselectively in positions 1 and 5 of naphthalene (4). The key for this electroconversion is boron‐doped diamond as the anode material. The method of the multi‐amination reaction is expanded to other aromatic substrates. A detailed study is provided, covering electrolysis parameters such as anode material, electrolyte system, current density, separator, and so forth. Despite the moderate yields, this approach offers the first direct electrosynthetic access to diaminated products.

Synthetic Organic Electrochemical Methods Since 2000: On the Verge of a Renaissance

“…While Yoshida’s original condition works most effectively for electron-rich arenes such as anisole derivatives, Waldvogel expanded the scope to include electron-neutral substrates with the use of a BDD anode—even diamination has been demonstrated on some substrates. 319,320 In Waldvogel’s study, it was also noted that amination of the arene nucleus trumps benzylic functionalization for substrates substituted with alkyl appendages. An intramolecular variant of this method allowed access to 2-aminobenzoxazoles and benzothiazoles (Figure 19C).…”

Anodic Formation of Aryl Mesylates through Dehydrogenative Coupling Reaction

“…In a separate study exploring the direct amination of arenes via pyridinium intermediates, naphthalene was investigated . During the optimization, different supporting electrolytes with a better environmental footprint, due to e. g. a lower environmental persistence, were studied.…”

“…The sterically more hindered mesylate 18 was obtained in a significantly higher yield. The same selectivity for the functionalization of 2,6‐dimethylnaphthalene has already been observed for the electrochemical amination . In case of phenanthrene, 9‐phenanthryl methanesulfonate ( 20 ) was isolated in a yield of 24 % along with 4 % of 9,10‐phenanthrenequinone, resulting from over‐oxidation of phenanthrene.…”

Elektrifizierung der organischen Synthese

“…[45] This method provides an innovative access to the technically important bulk chemical 1,5-diaminonaphthalene. Aromatic diamines are valuable precursors for the synthesis of polyurethanes,i ndispensable in our daily life.…”

“…Twofold electrochemical CÀHa mination of naphthalene. [45] Scheme 8. Electrochemical amination of benzoxazoles through oxidative dehydrogenativecouplings.…”