Direct Alkenylation and Alkylation of Pyridone Derivatives by Ni/AlMe₃ Catalysis

Abstract

Regioselective alkenylation and alkylation of 2-pyridone derivatives are achieved through inter- and intramolecular insertion of alkynes, 1,3-dienes, and alkenes into the C(6)-H bond by nickel/AlMe(3) catalysis. Coordination of the heterocycles to the Lewis acid cocatalyst through their basic carbonyl oxygen is considered to be responsible for the regioselective activation of the C-H bonds, probably through oxidative addition to nickel(0).

Regioselective C−H Hydroarylation of Internal Alkynes with Arenecarboxylates: Carboxylates as Deciduous Directing Groups

“…[4] C À Hh ydroarylations of alkynes are advantageous over these processes,b ecause they require neither prefunctionalized substrates nor oxidants.S ince the pioneering studies by Murai and co-workers, [5] various metals have been found to efficiently catalyze the hydroarylation of alkynes,for example Ru, [6] Rh, [7] Re, [8] Co, [9] and others. [10] However, these CÀH functionalizations are highly regioselective only when directed by ketone,p yridine,a mide,s ulfoxide,o ro ther strong directing groups,groups which need to be synthesized in additional reaction steps and are not easily removed.…”

Nickel‐ and Cobalt‐Catalyzed Direct Alkylation of Azoles with N‐Tosylhydrazones Bearing Unactivated Alkyl Groups

“…A few successful examples with alkyl halides are still restricted in substrate scope to cyclic frameworks, such as cyclohexane and cyclopentane. [4b,g, 6] A metal-catalyzed C À H insertion approach with alkenes, [7] and a copper-catalyzed alkylation with N-tosylhydrazones, which has very recently been reported by Wang and co-workers (see below), [8] appear to be good alternatives, however, these processes are limited to activated systems, thus only enabling benzylation and allylation. Therefore, further developments for more general alkylation methodologies are strongly desired.…”

Recent advances on nickel-catalyzed C–H bonds functionalized reactions

“…This study reveal that Lewis acid plays a critical role in activating the formamides towards C(sp 2 )-H activation. 29,30 With this Lewis-acid assistance, [Ni] oxidatively adds the C(sp 2 )-H bond of the formamide. Alkyne insertion followed by C-C bond-forming reductive elimination provides highly substituted acrylamides.…”