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<p><i>C</i>-heteroaryl glycosides, predominantly in unprotected forms, are common entities in bioactive molecules and have extensive applications in chemistry and biology. However, the chemical synthesis of these glycosides remains challenging owing to the lack of methods that directly leverage naturally occurring (native) sugars as substrates. Here we show that fully unprotected native sugars, capped as redox-active glycosyl sulfide donors, can be merged with <i>N</i>-heteroarenes in the presence of triethylamine and a photocatalyst under mild visible-light irradiation. The C–C coupling transformation proceeds with control over chemo-, site- and stereoselectivities and is compatible with a diverse range of <i>N</i>-heteroarenes bearing acidic and basic functional groups. The utility of this method is highlighted by the glycosylation of nucleosides, as well as by the direct coupling of <span>d</span>-mannose with pentoxifylline to generate a compound exhibiting glycogen-metabolism-inhibitory properties. In contrast to previously established mechanisms, the photocatalytic species is found to trigger the in situ generation of a thiyl radical that promotes hydrogen atom transfer to afford the target product, with triethylamine serving as a reductant through photoinduced charge-transfer complexation with the glycosyl sulfide.</p><p></p>

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Photocatalytic coupling of unprotected sugars and N-heteroarenes

  • 期刊论文

  • 发表日期：

    2026年1月19日

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  • Qian-Yi Zhou,
  • Daniel Zhi Wei Ng,
  • Jun Wu,
  • Wei Liang Leow,
  • Songge Li,
  • Eric Chun Yong Chan,
  • Ming Joo Koh

摘要

C-heteroaryl glycosides, predominantly in unprotected forms, are common entities in bioactive molecules and have extensive applications in chemistry and biology. However, the chemical synthesis of these glycosides remains challenging owing to the lack of methods that directly leverage naturally occurring (native) sugars as substrates. Here we show that fully unprotected native sugars, capped as redox-active glycosyl sulfide donors, can be merged with N-heteroarenes in the presence of triethylamine and a photocatalyst under mild visible-light irradiation. The C–C coupling transformation proceeds with control over chemo-, site- and stereoselectivities and is compatible with a diverse range of N-heteroarenes bearing acidic and basic functional groups. The utility of this method is highlighted by the glycosylation of nucleosides, as well as by the direct coupling of d-mannose with pentoxifylline to generate a compound exhibiting glycogen-metabolism-inhibitory properties. In contrast to previously established mechanisms, the photocatalytic species is found to trigger the in situ generation of a thiyl radical that promotes hydrogen atom transfer to afford the target product, with triethylamine serving as a reductant through photoinduced charge-transfer complexation with the glycosyl sulfide.