Electrochemical bromofunctionalization of alkenes in a flow reactor

The bromination of organic molecules has been extensively studied to date, yet there is still a demand for safe and sustainable methodologies. Hazardous reagents, selectivity, low atom economy and waste production are the most persisting problems of brominating reagents. The electrochemical oxidation of bromide to bromine is a viable strategy to reduce waste by avoiding chemical oxidants. Furthermore, the in situ generation of reactive intermediates minimizes the risk of hazardous reagents. In this work, we investigate the electrochemical generation of bromine from hydrobromic acid in a flow electrochemical reactor. Various alkenes could be converted to their corresponding dibromides, bromohydrines, bromohydrin ethers and cyclized products in good to excellent yields.

3-Methyl-4-oxo-2-phenyl-4H-chromene-8-carboxylic acid

In the title compound, C₁₇H₁₂O₄, the chromene unit is approximately planar, the maximum deviation from the mean plane being 0.0166 Å. The attached phenyl ring makes a dihedral angle of 53.2 (1)° with the fused ring system. The packing of the mol­ecules in the crystal structure is governed by C—H⋯O and O—H⋯O hydrogen-bonding inter­actions.