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DOI: 10.1055/s-0030-1260522
Synthesis of 3-Aminobenzofurans via Cu-Catalyzed Annulative Amination
K. Hirano*, T. Satoh, M. Miura*
Osaka University, Suita, Japan
Publication History
Publication Date:
17 June 2011 (online)
Significance
Reported is an effective copper-catalyzed annulative amination of ortho-alkynylphenols 1 with O-acylated hydroxylamine 2 yielding 3-aminobenzofurans 3. The transformation involved an annulative cupration of ortho-alkynyl-phenols (R. Alvarez et al. Chem. Eur. J. 2010, 16, 12746) followed by electrophilic C-N bond formation. The reaction was effected in the presence of Cu(OTf)2 and LiOt-Bu as base in aprotic solvent (NMP) under optimized conditions. The scope was explored primarily with R³ variation (EWGs and EDGs). ortho-Alkynyl hydroxythiophenes also participated in the reaction. Allylamine, benzylamine, and cyclic amines (morpholine, piperidine or tetrahydroisoquinoline) were also shown to be tolerated in the reaction.