Reactions of Aromatic Heterocycles with Uranium Alkyl Complexes

Abstract

The reactivity of a uranium dibenzyl complex supported by a ferrocenediamide ligand toward aromatic N-heterocycles was investigated. The uranium dibenzyl complex reacted with 1 equiv of pyridine or picoline to give the respective ortho-metalated product. In turn, the eta(2)-N,C-pyridyl complexes reacted with benzoxazole or benzothiazole, leading to a cascade of transformations that involves C-C coupling of the two heterocyclic rings, ring opening, and alkyl transfer. A similar cascade was previously reported for 1-methylimidazole. The present results provide support for the mechanism proposed earlier and attest to the generality of the reaction cascade described.

Ring opening of aromatic heterocycles by uranium complexes

“…The mechanistic proposal shown in Scheme 1 was supported by the analogous reactions of a pyridylebenzyl complex with benzoxazole and benzothiazole [30] and by the characterization of a CeC coupled product based on 1-methylbenzimidazole [31,36]. This complex, 3 mbi , is analogous to 3 mi (shown in Scheme 1).…”

Rare Earth Arene-Bridged Complexes Obtained by Reduction of Organometallic Precursors

“…The electron donating 1,1′-ferrocenediyl group (Sauro and Workentin, 2002) makes the amide donor bind strongly to the highly electropositive group 3 metals and uranium(IV) ion. By using NN TBS as the ancillary ligand for d 0 f n metal alkyl complexes, the C-H bond activation of aromatic heterocycles , successive C-C bond coupling Carver et al, 2010;Monreal and Diaconescu, 2010;Williams et al, 2010), dearomatization of aromatic heterocycles , and the unprecedented ring-opening of 1-methylimidazole Monreal et al, 2009), 1-methylbenzimidazole , or other aromatic heterocycles (Duhović et al, 2010) were observed and studied (Diaconescu, 2010a;Diaconescu, 2010b).…”

Yttrium-Alkyl Complexes Supported by a Ferrocene-Based Phosphinimine Ligand

“…[14][15][16] Our group has studied extensively the reactivity of group 3 metals and uranium alkyl complexes supported by diamide ligands towards heterocyclic aromatic compounds. [17][18] Benzyl complexes were found to ring open 1-methylimidazoles, [19][20][21][22][23] effect C-C coupling of pyridines, [24][25] and alkyl transfer to isoquinoline. [26][27] In those cases, the ligand framework was a ferrocenediamide that could support a weak donor-acceptor interaction between the metal in the ligand.…”