A simple, effective, green method for regioselective 3-acylation of unprotected indoles

Phuong Huong Tran, Hai N. Tran, Poul Erik Hansen, Mai Hoang Ngoc Do, Thach N Le

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A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized
Udgave nummer10
Sider (fra-til)19605-19619
Antal sider15
StatusUdgivet - 2015


  • indoles
  • Friedel-Crafts
  • acylation
  • green chemistry
  • ionic liquids
  • ytterbium triflate
  • microwave

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