Transition Metal Catalyzed Insertion Reactions with Donor/Donor Carbenes

Abstract

Donor/donor carbenes are relatively new in the field of carbene chemistry; although applications in C−H and X−H insertion reactions are few in number, they demonstrate exquisite chemo‐ and stereo‐selectivity. Recent reports have shown that C−H, N−H, B−H, O−H, S−H, Si−H, Ge−H, Sn−H and P−H insertion reactions are feasible with a variety of transition metal catalysts, both inter‐ and intramolecularly. Furthermore, high degrees of diastereo‐ and enantioselectivity have been observed in several cases. Methods typically involve the formation of a diazo‐based carbene precursor, but procedures using diazo‐free metal carbenes have been developed with significant success. This Minireview covers transition‐metal catalyzed insertion reactions with donor/donor and donor carbenes, providing context for future developments in this emerging field.

Metal Bound or Free Ylides as Reaction Intermediates in Metal-Catalyzed [2,3]-Sigmatropic Rearrangements? It Depends

“…They are often categorized into five main groups: i.e. acceptor, 27,28 acceptor/acceptor, 29,30 donor/acceptor, 26,31,32 donor, 33 and donor/donor [34][35][36][37][38][39] (Scheme 1a), depending on the electron withdrawing or donating ability of substituents adjacent to the carbene center. This versatility in functional group discretion enables one to fine-tune the reactivity and selectivity of the carbene intermediate, which make Rh carbenes amenable to a wide range of chemical transformations.…”

A New Ligand Design Based on London Dispersion Empowers Chiral Bismuth–Rhodium Paddlewheel Catalysts

“… 81 With catalyst 3b , these challenging substrates react even at −10 °C. Likewise, donor/donor carbenes are well behaved, 2 , 82 , 83 again furnishing the corresponding cyclopropanes with outstanding levels of enantio- and diastereoselectivity (entries 26–28).…”

Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung

“…), the reaction to brominated 4n was less selective, indicating the boundaries of enantioselection of the method. Consistent with the stereoselectivity for acyclic rhodium diarylcarbenes, [41][42][43] electronic effects of the substituents may impact stereocontrol by differentiating the torsion angles between the aryl groups and the rhodium carbene, albeit to a reduced extent within the cyclic structures compared to open analogs. Altogether, the comprehensive scope underscores the capacity of chiral dirhodium tetracarboxylate catalysts for diazo-thioketone couplings through Rh-carbenoids by the unique stereoselective thiiranation, whereas the breadth of the approach for distinct bistricyclic aromatic ene stereoisomers is highlighted by the remarkable stereospecificity of the thiirane reduction.…”