Regiocontrol in catalytic reductive couplings through alterations of silane rate dependence

J Am Chem Soc. 2015 Jan 21;137(2):958-63. doi: 10.1021/ja511778a. Epub 2015 Jan 5.

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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Catalysis
  • Kinetics
  • Reducing Agents / chemistry*
  • Silanes / chemistry*
  • Stereoisomerism
  • Substrate Specificity

Substances

  • Reducing Agents
  • Silanes