The metal-free stereoselective procedure is developed by using selectfluor and TBAB as a reagent system for the dibromination of sugar enol-ethers and monobromination of heterocyclic compounds. This protocol attained dibrominated product with glycals in 5 minutes at room temperature with excellent yields. For substituted indoles and chromones, same reagent system delivered the 3-brominated products but at elevated temperatures. Further, the synthetic utility was shown by synthesizing 3-aryl indoles and isoflavones via Suzuki-Miyura cross-coupling reactions.

Abstract

Herein, we have devised a metal-free stereoselective protocol mediated by selectfluor for the dibromination of sugar enol-ethers and monobromination of heterocyclic compounds. The dibromination of glycals was achieved within 5 minutes at room temperature with excellent yields. The tolerance of various protecting groups such as acetyl, benzyl, and silyl in sugars was checked. When the same reagent system was applied to substituted indoles and chromones 3-brominated products were obtained but at elevated temperatures. The synthetic utility of the methodology was demonstrated by using the brominated indoles and chromones to synthesize the 3-aryl indoles and isoflavones respectively via Suzuki-Miyura cross-coupling reactions.