Unusual rearrangements in activated indoles: Synthesis of indoloquinolines, dibenzonaphthyridines and indolobenzodiazepines

Reaction of 2-arylindoles with 2-acetamidobenzyl chloride gave 3-alkylated indoles rather than those substituted at nitrogen. Similar reactions with 3-arylindoles gave reduced indoloquinolines, and a 2,3-diphenylindole gave a 3-alkylated indole. On reaction with phosphoryl chloride, the amidobenzylindoles undergo rearrangement to benzonaphthyridines. Similarly, the indoloquinolines undergo rearrangement to benzodiazepino-indoles. (C) 2020 Elsevier Ltd. All rights reserved.