Analysing the reaction of a β-diketone with dimethyl sulphoxide (DMSO)/acetic anhydride

To study the reaction between a β-diketone and dimethyl sulphoxide (DMSO)/acetic anhydride to synthesize a novel chemical entity. o-Hydroxyacetophenone was esterified with p-chlorobenzoic acid using POCl3. The obtained ester was subjected to a B.V. rearrangement in a solution of KOH in pyridine solution under anhydrous conditions. This process produced a β-diketone that was reacted with acetic anhydride in DMSO to give p-chloroflavone. The structures of all of the compounds were confirmed using nuclear magnetic resonance (NMR) spectral data. Further proof of the structure of the compound was obtained by cyclization of the diketone by heating it in a solution of sodium acetate in glacial acetic acid. The obtained compound was identical to the flavone obtained by reacting the β-diketone with DMSO and acetic anhydride. The β-diketone obtained from the reaction of the ester of o-hydroxy acetophenone and p-chlorobenzoic acid was transformed to a flavone upon reaction with DMSO/acetic anhydride. β-Diketones can be cyclized with DMSO/acetic anhydride to synthesize flavones.