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J Am Chem Soc. 2012 Oct 17;134(41):17003-6. doi: 10.1021/ja308460z. Epub 2012 Oct 5.

Catalytic enantioselective cross-couplings of secondary alkyl electrophiles with secondary alkylmetal nucleophiles: Negishi reactions of racemic benzylic bromides with achiral alkylzinc reagents.

Author information

1
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.

Abstract

We have developed a nickel-catalyzed method for the asymmetric cross-coupling of secondary electrophiles with secondary nucleophiles, specifically, stereoconvergent Negishi reactions of racemic benzylic bromides with achiral cycloalkylzinc reagents. In contrast to most previous studies of enantioselective Negishi cross-couplings, tridentate pybox ligands are ineffective in this process; however, a new, readily available bidentate isoquinoline-oxazoline ligand furnishes excellent ee's and good yields. The use of acyclic alkylzinc reagents as coupling partners led to the discovery of a highly unusual isomerization that generates a significant quantity of a branched cross-coupling product from an unbranched nucleophile.

PMID:
23039358
PMCID:
PMC3474870
DOI:
10.1021/ja308460z
[Indexed for MEDLINE]
Free PMC Article

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