A competitive and highly selective 7-, 6- and 5-annulation with 1,3-migration through C-H and N-H - alkyne coupling
Sk Ajarul1, Anirban Kayet, Tanmay K Pati
1Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata-700009, India. dkmchem@caluniv.ac.in.
Abstract:
We demonstrated a highly competitive and selective C-C and N-C cross-coupled 7-, 6- and 5-annulation utilizing 2-ethynylanilides to afford functionalized 1H-benzo[b]azepin-2(5H)-ones, 2-quinolinones, and 3-acylindoles in high yield. ZnCl2 was found to be the smart catalyst for 7- and 5-annulation with 1,3-migration through C-H and N-H functionalization, respectively, whereas molecular iodine performed the C-H functionalized 6-annulation with a nonconventional 1,3 H-shift. The mechanism was investigated by intermediate trapping, control, and labeling experiments.
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