RESUMO
[This corrects the article DOI: 10.1039/C4SC03106G.].
RESUMO
Cross-electrophile coupling of aryl halides with alkyl halides has thus far been primarily conducted with stoichiometric metallic reductants in amide solvents. This report demonstrates that the use of tetrakis(dimethylamino)ethylene (TDAE) as an organic reductant enables the use of non-amide solvents, such as acetonitrile or propylene oxide, for the coupling of benzyl chlorides and alkyl iodides with aryl halides. Furthermore, these conditions work for several electron-poor heterocycles that are easily reduced by manganese. Finally, we demonstrate that TDAE addition can be used as a control element to 'hold' a reaction without diminishing yield or catalyst activity.
RESUMO
The nickel-catalyzed cross-coupling of aryl halides with alkyl radicals derived from alkyl halides has recently been extended to couplings with carbon radicals generated by a co-catalyst. In this study, a new co-catalyst, cobalt phthalocyanine (Co(Pc)), is introduced and demonstrated to be effective for coupling substrates not prone to homolysis. This is because Co(Pc) reacts with electrophiles by an SN2 mechanism instead of by the electron-transfer or halogen abstraction mechanisms previously explored. Studies demonstrating the orthogonal reactivity of (bpy)Ni and Co(Pc), applying this selectivity to the coupling of benzyl mesylates with aryl halides, and the adaptation of these conditions to the less reactive benzyl phosphate ester and an enantioconvergent reaction are presented.
RESUMO
[This corrects the article DOI: 10.1039/C4SC03106G.].
RESUMO
A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates.