Simple and Regioselective Bromination of 5,6-Disubstituted-indan-1-ones with Br2 Under Acidic and Basic Conditions

Abstract

Bromination of 5,6-dimethoxyindan-1-one with Br2 in acetic acid at room temperature produced exclusively the corresponding 2,4-dibromo compound in 95% yield. Reaction of 5,6-dimethoxyindan-1-one with Br2 in the presence of KOH, K2CO3 or Cs2CO3 at ~0°C gave the monobrominated product 4-bromo-5,6-dimethoxyindan-3-one in 79%, 81% and 67% yield, respectively. 5,6-Dihydroxyindan-1-one was dibrominated on the aromatic ring affording 4,7-dibromo-5,6-dihydroxyindan-1-one both in acetic acid at room temperature and in the presence of KOH at ~0°C. 5,6-Difluoroindan-1-one and 1-indanone were α-monobrominated in acetic acid and α,α-dibrominated under KOH conditions at room temperature.

Keywords

• 5
• 6-Dimethoxyindan-1-one
• 5
• 6-dihydroxyindan-1-one
• regioselective aromatic bromination
• α-bromination.