Nickel-catalyzed C–N bond activation: activated primary amines as alkylating reagents in reductive cross-coupling

Abstract

The reductive cross coupling of pyridinium salts derived from readily available primary alkyl amines with aryl halides has been achieved under mild reaction conditions using a nickel catalyst.

Pyridinium Salts as Redox‐Active Functional Group Transfer Reagents

“…Although organometallic reagents constitute aw idely available class of nucleophilic cross-coupling partners,t he coupling of two electrophiles can offer several distinct advantages. [34] To this end, the groups of Rueping, [35] Watson, [36] and Martin [37] have independently developed an ickel-catalyzed reductive cross-coupling of C(sp 2 )h alides with N-alkyl pyridinium salts 1 (Scheme 4). Theconditions in all three methods differ slightly;h owever, Mn powder was identified as the optimal stoichiometric reductant in all cases and elevated temperatures were required in most examples.…”

Pyridiniumsalze als redoxaktive Reagenzien zur Übertragung funktioneller Gruppen

“…Während metallorganische Reagenzien eine weit verbreitete Klasse von nukleophilen Kreuzkupplungspartnern darstellen, kann die Kupplung zweier Elektrophiler mehrere entscheidende Vorteile bieten . Zu diesem Zweck haben die Gruppen von Rueping, Watson und Martin unabhängig voneinander eine nickelkatalysierte, reduktive Kreuzkupplung von C(sp 2 )‐Halogeniden mit den N ‐Alkylpyridiniumsalzen 1 entwickelt (Schema ). Die Bedingungen bei allen drei Methoden unterscheiden sich leicht, jedoch wurde Mn‐Pulver in allen Fällen als das optimale stöchiometrische Reduktionsmittel identifiziert, und in den meisten Beispielen werden erhöhte Temperaturen benötigt.…”

N-Heterocyclic carbene-catalyzed deaminative cross-coupling of aldehydes with Katritzky pyridinium salts

“…Recently, Katritzky pyridinium salts, easily prepared from the condensation of primary amines with commercially available pyrylium salts, have emerged as a powerful tool for the generation of alkyl radical species. 3 Watson, 4 Glorius, 5 Aggarwal, 6 Shi, 7 Gryko, 8 Xiao, 9 Martin, 10 Rueping, 11 and Molander 12 have demonstrated the utility of Katritzky salts to form various types of C-C and C-B bonds via deaminative cross-coupling under Nicatalyzed or photomediated conditions (Scheme 1a). Despite the impressive achievements in this eld, a synthetic method that efficiently transforms an amine functionality into a carbonyl group via a deaminative radical pathway is still underexplored.…”