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Regiocontrol in catalytic reductive couplings through alterations of silane rate dependence.

ABSTRACT: Combinations of ligand, reducing agent, and reaction conditions have been identified that allow alteration in the rate- and regioselectivity-determining step of nickel-catalyzed aldehyde-alkyne reductive couplings. Whereas previously developed protocols involve metallacycle-forming oxidative cyclization as the rate-determining step, this study illustrates that the combination of large ligands, large silanes, and elevated reaction temperature alters the rate- and regiochemistry-determining step for one of the two possible product regioisomers. These modifications render metallacycle formation reversible for the minor isomer pathway, and σ-bond metathesis of the metallacycle Ni-O bond with the silane reductant becomes rate limiting. The ability to tune regiocontrol via this alteration in reversibility of a key step allows highly regioselective outcomes that were not possible using previously developed methods.

SUBMITTER: Jackson EP

PROVIDER: S-EPMC4356119 | biostudies-literature | 2015 Jan

REPOSITORIES: biostudies-literature

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Regiocontrol in catalytic reductive couplings through alterations of silane rate dependence.

Jackson Evan P EP Montgomery John J

Journal of the American Chemical Society 20150105 2

Combinations of ligand, reducing agent, and reaction conditions have been identified that allow alteration in the rate- and regioselectivity-determining step of nickel-catalyzed aldehyde-alkyne reductive couplings. Whereas previously developed protocols involve metallacycle-forming oxidative cyclization as the rate-determining step, this study illustrates that the combination of large ligands, large silanes, and elevated reaction temperature alters the rate- and regiochemistry-determining step f ...[more]

PMID: 25531576

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