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Keywords:

  • annulation;
  • carbenes;
  • redox reaction;
  • spiro compounds;
  • umpolung
Thumbnail image of graphical abstract

Smooth as isatin! A straightforward synthesis of spirocyclic oxindole–dihydropyranones through an N-heterocyclic-carbene-catalyzed [4+2] annulation of α-bromo-α,β-unsaturated aldehydes or α,β-dibromoaldehyde bearing γ-H with isatin derivatives under mild reaction conditions is disclosed (see scheme). The concise construction, ready availability of the starting materials, avoidance of external oxidants, and the potential utilization value of final products in molecular biology and pharmacy makes this approach particularly attractive.