Metal‐Catalyzed Quinoid Carbene ( QC ) Transfer Reactions

Organometallic catalysis in aqueous and biological environments: harnessing the power of metal carbenes

“…47 However, the most widely used carbene precursors are diazo compounds, which are reasonably stable but can readily decompose to carbenes under mild reaction conditions. 44,48 The resulting free carbenes tend to be highly reactive, and therefore difficult to use in chemical transformations; however, upon appropriate coordination to transition metals they give metal carbenes, which present a more controllable and rich reactivity. The chemical properties of these metal complexes depend on the spin configurations of the carbene, and on the overlap with the metal orbitals.…”

“…The rich reactivity of metal carbenes is mostly related to the charge distribution along the metal–carbon bond and the electrophilicity of the carbene carbon, allowing its reaction with a variety of nucleophiles. Within the broad spectrum of reactions enabled by metal carbenes, most common transformations include cyclopropanations of alkenes, 51–53 C–H functionalizations, 49,54–56 insertions into X–H bonds (X = O, N, S, Si), 57,58 the formation of ylides 59–61 (and subsequent rearrangements) or cycloaddition processes 44,61 (Fig. 1c).…”

“…Metal carbene transfer reactions are among the most powerful and versatile transformations in catalysis and organometallic chemistry, and have been used for many synthetic applications. 44,45 Translating the rich reactivity typically exhibited by metal carbenes in organic solvents to aqueous and biological media, could open important new avenues in research at the interface between chemistry and biology.…”

Cu(II)-Catalyzed Construction of Heterobiaryls using 1-Diazonaphthoquinones: A General Strategy for the Synthesis of QUINOX and Related P,N Ligands

“…Arguably, site-selective catalytic C–H bond functionalizations would be one of such straightforward methods to construct these heterobiaryls. Recently, quinonediazides/diazonaphthalen-2­(1 H )-ones have been elegantly utilized to introduce phenol/naphthol moieties into C–H bonds with minimum waste via metal-carbene formation . Significant progress has been realized in the directed and nondirected insertion of a quinoid-carbene into C­(sp 2 )–H and C­(sp 3 ) C–H bonds for arylation. − …”

Palladium-catalyzed intramolecular enantioselective C(sp3)–H insertion of donor/donor carbenes

“…The asymmetric C–H insertion of metal carbene is one of the most powerful methods for the construction of chiral molecules through carbon–carbon bond formation. 1,2 In the past several decades, many transition metal complexes, especially dirhodium( ii ) complexes, 2,3 have emerged as effective catalysts for the enantioselective carbene C–H insertion reactions.…”