Carbon–carbon bond construction using boronic acids and aryl methyl sulfides: orthogonal reactivity in Suzuki-type couplings

Abstract

The Rh(I)-catalysed coupling of aryl and alkenyl boronic acids with simple aryl and alkenyl methyl sulfides is reported. The process employs bench-stable Rh(I) precatalysts incorporating small bite-angle chelating phosphine ligands (R 2 PCH 2 PR 2 , R ¼ i Pr, Cy), shows good functional group tolerance, and proceeds under mild reaction conditions. Importantly, aryl bromide activating groups are inert to the reaction conditions, allowing selective reaction at either a methyl sulfide or bromide activating group, depending on catalyst (metal) choice. The scope of the coupling reactions, their combination with Rh-catalysed hydroacylation reactions in cascade processes, together with preliminary mechanistic studies, are all documented.

The Synthesis, Characterization and Dehydrogenation of Sigma‐Complexes of BN‐Cyclohexanes

“…This is consistent with a rapid dimer/monomer equilibrium in which the dimer is dominant but sits off the cycle and a monomer is the active species. Such equilibria have been suggested before for arene alkylations, [72] alkene hydrogenation [65] and hydroboration, [73] amine–borane dehydrogenation, [58] C–S bond activations, [74] and arylation of BCl–1,2–azaborines, [75] amongst others. Perhaps most closely related to the system under discussion here are dimer/monomer equilibria operating for Shvo’s catalyst in both amine–borane dehydrogenation and hydrogen transfer reactions.…”

Oxidative Addition of Aryl Halides to Cationic Bis(phosphane)rhodium Complexes: Application in C–C Bond Formation

“…Our results add to those reported by Satoh, Miura and Ueura concerning the use of neutral dimeric rhodium complexes in combination with 1,3‐bis(diphenylphosphanyl)propane, 1,2‐bis(diphenylphosphanyl)ethane, 1,4‐bis(diphenylphosphanyl)butane and 1,1′‐bis(diphenylphosphanyl)ferrocene. [4e] Besides, cationic rhodium complexes bearing small‐bite‐angle bis(phosphanes) R 2 PCH 2 PR 2 (R = t Bu, Cy, i Pr) have also been reported as competent for a closely related transformation, namely, the coupling of simple boronic acids with aryl and alkenyl methyl sulfides …”

Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

“…Transition metal-catalyzed cross-coupling reactions have been instrumental to advancement in this realm, because these mild and functional group-tolerant methods are naturally amenable to the late-stage union of fully elaborated and minimally protected molecular fragments (1). Within this context, a variety of methods have been developed for iterative assembly of small-molecule scaffolds through orthogonal crosscoupling enabled by judicious attenuation of reactivity at either the organometallic or organic (pseudo-)halide site (2)(3)(4)(5).…”