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<p>Enantioconvergent cross-coupling offers a direct route from racemic starting materials to enantioenriched products, yet reactions using racemic alkylmagnesium reagents have remained largely unexplored because of their high reactivity and poor stereocontrol. Here we report a nickel-catalysed enantioconvergent coupling of racemic <i>α</i>-borylalkylmagnesium species, generated in situ via deborylative transmetalation of <i>gem</i>-diborylalkanes with magnesium halides, with unactivated alkyl iodides. This protocol delivers a broad range of enantioenriched alkylboronic esters in high yields and with excellent enantioselectivities. Mechanistic studies, including electrospray ionization-mass spectrometry, radical-clock experiments and computational calculations, support the formation of <i>α</i>-borylalkylmagnesium intermediates and provide insight into the enantioconvergent stereochemical outcome. The synthetic utility of the method is demonstrated through late-stage couplings, gram-scale reaction and modular access to pharmaceutical intermediates from commercially available diborylmethane. By overcoming long-standing limitations associated with racemic alkylmagnesium reagents in enantioconvergent coupling, this work provides a general strategy for enantioselective alkyl–alkyl bond formation using racemic organomagnesium nucleophiles.</p><p></p>

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Enantioconvergent alkylation of boron-stabilized organomagnesiums with unactivated alkyl halides using nickel catalysis

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Semin Lee,
  • Seungcheol Han,
  • Joeun Choi,
  • Seung Hwan Cho

摘要

Enantioconvergent cross-coupling offers a direct route from racemic starting materials to enantioenriched products, yet reactions using racemic alkylmagnesium reagents have remained largely unexplored because of their high reactivity and poor stereocontrol. Here we report a nickel-catalysed enantioconvergent coupling of racemic α-borylalkylmagnesium species, generated in situ via deborylative transmetalation of gem-diborylalkanes with magnesium halides, with unactivated alkyl iodides. This protocol delivers a broad range of enantioenriched alkylboronic esters in high yields and with excellent enantioselectivities. Mechanistic studies, including electrospray ionization-mass spectrometry, radical-clock experiments and computational calculations, support the formation of α-borylalkylmagnesium intermediates and provide insight into the enantioconvergent stereochemical outcome. The synthetic utility of the method is demonstrated through late-stage couplings, gram-scale reaction and modular access to pharmaceutical intermediates from commercially available diborylmethane. By overcoming long-standing limitations associated with racemic alkylmagnesium reagents in enantioconvergent coupling, this work provides a general strategy for enantioselective alkyl–alkyl bond formation using racemic organomagnesium nucleophiles.