Baker–Venkataraman rearrangement

[3][4][5][6][7][8][9][10] After the base-catalyzed rearrangement, treatment with acid generally affords the chromone or flavone core, though other milder methods have been reported.

[11] A base abstracts the hydrogen atom alpha to the aromatic ketone, forming an enolate.

Then, the enolate attacks the ester carbonyl to form a cyclic alkoxide.

The cyclic intermediate is opened up to form a more stable phenolate, which is protonated during acidic work-up to give the desired product.

This was commonly afforded by treatment with strong acid, however many milder conditions have now been developed.