Facile C–H bond activation on a transient gallium imide

Abstract

Reaction of NacNacGa with azide N3SiMe3 results in the generation of a transient imide NacNacGa(=NSiMe3) that can cleave unactivated sp3C-H and sp2C-H bonds of different substrates, affording gallium amides. Pyridine,...

Reactions of main group compounds with azides forming organic nitrogen-containing species

“…94 In 2022, Nikonov and co-workers investigated the transient gallium imide to active C-H bonds. 95 Treatment of the mixed solution of Ga2 with one equivalent of TMSN 3 in the presence of various substrates (pyridine, cyclohexanone, ethyl acetate, dimethyl sulfoxide, triethylphosphine oxide) produced the respective C-H bond activation product Ga2-P4 to Ga2-P8 in high yields (Scheme 52a). In order to trap the transient gallium imide GaQN intermediate, the reaction of Ga2 with TMSN 3 was conducted at low temperature in the presence of carbene (Scheme 52b).…”

Reactions of Low-Valent Gallium Species with Organic Azides: Formation of Imido-, Azoimido-, and Tetrazene Complexes

“…It has been reported that the highly polarized MN bond (M = Al, In) in the imido intermediates can undergo further C–H activation of either the supporting ligand ,, or the benzylic C–H bond of solvent toluene across the AlN bond of the imide . Reaction of NacNacGa with organic azide N 3 SiMe 3 leads to the formation of a transient imide NacNacGaNSiMe 3 that can break unreactive sp 3 and sp 2 C–H bonds of different substrates (cyclohexanone, pyridine, DMSO, ethyl acetate, and OPEt 3 ), affording gallium alkyl (or aryl) amides [NacNacGaR­(NHSiMe 3 )] . Therefore, the formation of 10 and 11 might provide evidence for the in situ generation of an anionic gallium imide species from 3 and an azide reagent.…”

“…22 Reaction of NacNacGa with organic azide N 3 SiMe 3 leads to the formation of a transient imide NacNacGa�NSiMe 3 that can break unreactive sp 3 and sp 2 C−H bonds of different substrates (cyclohexanone, pyridine, DMSO, ethyl acetate, and OPEt 3 ), affording gallium alkyl (or aryl) amides [NacNacGaR(NHSiMe 3 )]. 52 Therefore, the formation of 10 and 11 might provide evidence for the in situ generation of an anionic gallium imide species from 3 and an azide reagent.…”

1,3-C–H bond activation on a transient gallium(i)/isocyanate adduct

“…To test this hypothesis, one equivalent of PhNCO was added to a mixture of 1 and pyridine, but unlike the analogous reactions of 1 /pyridine with N 2 O 9 and azide, 10 there was no C–H addition and the only isolable product was the cyclic compound 4 , formed in 50% yield. However, when 1 was reacted with a 1 : 1 mixture of isocyanate and pyridine-oxide, the desired 2-pyridyl N -oxide derivative 6 was observed (Scheme 4) and isolated in the 43% yield.…”

“…8 We have recently found that oxidation of a Ga(I) compound, NacNacGa (1, NacNac = [(ArNvCMe) 2 CH] − ), by N 2 O or pyridine oxide, or its imidation with azides, N 3 R generates transient gallium oxide and imide NacNacGavX (X = O (2) or NR (3)), respectively, that can add in situ to non-activated C-H bonds of aliphatic and aromatic substrates, featuring good coordinating groups, such as pyridine, PvO and SvO bonds (Scheme 2). 9,10 In the course of our studies on the reactivity of 1 towards unsaturated molecules, we discovered that addition of 1 to isocyanates generates a transient species that is amenable to a novel 1,3-C-H addition. The results of these studies are reported herein.…”