Trans-metal-trapping meets FLP chemistry : Ga(CH2SiMe3)3 induced C-H functionalizations

Uzelac, Marina and Kennedy, Alan R. and Hevia, Eva (2017) Trans-metal-trapping meets FLP chemistry : Ga(CH2SiMe3)3 induced C-H functionalizations. Inorganic Chemistry. ISSN 0020-1669

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    Abstract

    Merging two topical themes in Main Group chemistry, namely cooperative bimetallics and FLP activity, this Forum Article focuses on the cooperativity-induced outcomes observed when the tris(alkyl)gallium compound GaR3 (R= CH2SiMe3) is paired with lithium amide LiTMP (TMP=2,2,6,6-tetramethylpiperidide) or the sterically hindered NHC ItBu (ItBu = 1,3-bis(tert-butyl)imidazol-2-ylidene). Drawing together some previously published work with new results, unique tandem reactivities are presented which are driven by the steric mismatch between the individual reagents of these multicomponent reagents. Thus the LiTMP/GaR3 combination, which on its own fails to form a co-complex, functions as a highly regioselective base (LiTMP)-trap (GaR3) partnership for metalation of N-heterocycles such as diazines, 1,3 benzo-azoles and 2-picoline in a trans-metal-trapping (TMT) process that stabilizes the emerging sensitive carbanions. Taking advantage of related steric incompatibility, a novel monometallic FLP system pairing GaR3 with ItBu has been developed for activation of carbonyl compounds (via C=O insertion) and other molecules with acidic hydrogen atoms such as phenol and phenylacetylene. Shedding new light on how these non-cocomplexing partnerships operate and showcasing the potential of Ga reagents to engage in metalation reactions or FLP activations, areas where the use of this Group 13 metal is scant, this Forum Article aims to stimulate more interest and activity towards the advancement of organogallium chemistry.