Gold-catalyzed para-selective C–H bond alkylation of benzene derivatives with donor/acceptor-substituted diazo compounds

Abstract

Herein, we report a gold-catalyzed highly site-selective C(sp)-H functionalization of unactivated arenes with α-aryl-α-diazoesters with electron-withdrawing substituents as induced groups on aryl rings. Furthermore, the induced groups are useful for further synthetic transformations.

Gold‐catalyzed C−H Functionalization of Phenothiazines with Aryldiazoacetates

“…[13] Instead, only decomposition of the diazoalkane 7 a was detected ( Table 1, entries 1-5). Fortunately, Au(I) based catalysts were found to promote the reaction quite well to give the CÀ H functionalization product 6 a (Table 1, entries [7][8][9][10][11][12][13][14][15] where the reaction occurred at the para-position (C-3) to the nitrogen center. Notably, only a minor background reaction in the presence of Ag(I) catalysts was observed (Table 1, entry 6 and Table S1 in ESI).…”

“…Specifically, the carbocationic reactivity of the gold-carbene complexes allows straightforward para CÀ H functionalization of electron-rich aromatic systems such as phenols, naphthols, anilines, or carbazoles. [9,10] The challenge of the CÀ H functionalization of PTZs lies within many potential chemo-and regioselectivity issues that might arise from reactions on the phenothiazine framework. [3] As two different heteroatoms are present within the heterocyclic skeleton, up to four different products can potentially arise from mono CÀ H functionalization, which would diminish the overall efficiency of this reaction.…”

Isolation of a Reactive Tricoordinate α‐Oxo Gold Carbene Complex

“…To confirm the critical role of the gold carbene electrophilicity on the C−H versus O−H insertion selectivity, we envisioned to introduce electron‐withdrawing groups in remote positions of the phenyl substituent of the carbene . We selected the bis(CF 3 ) diazo compound 1‐CF 3 and tested its reactivity towards phenol under the same conditions than for 1 (5 mol % of complex 2 at room temperature, Scheme ).…”

Efficient Approaches for the Synthesis of Diverse α-Diazo Amides

“…[2][3][4] Crucially, judicious choice of catalyst can provide control over stereochemistry, chemoselectivity (e.g., a particular C-H bond in a complex substrate) and reaction fate (e.g., which mode of reactivity is favoured). [5][6][7][8][9][10] The diversity of possible reaction outcomes can enable the parallel discovery of diverse bioactive chemotypes. 11,12 We therefore investigated a suite of methods for the synthesis of -diazo amides and some related compounds.…”