Efficient Microwave‐Assisted Synthesis of α,β ‐Unsaturated Ketones Based on a Pyrano[2,3‐f]chromene‐4,8‐dione Scaffold

A concise microwave‐assisted protocol has been established for the efficient synthesis of novel α,β ‐unsaturated ketones bearing a pyrano[2,3‐ f ]chromene‐4,8‐dione core. The pivotal intermediate, 3‐acetyl‐2,10‐dimethyl‐4 H ,8 H ‐pyrano[2,3‐ f ]chromene‐4,8‐dione, was obtained in 78% yield via a Kostanecki–Robinson reaction and subsequently transformed into a series of thirteen derivatives ( 5a – 5m ) through Claisen–Schmidt condensations with aromatic aldehydes, providing the target compounds in high isolated yields (74%–94%) within 10 min under optimized microwave conditions. Structural identities of all compounds were unambiguously confirmed by comprehensive spectroscopic analyses. Preliminary antioxidant evaluation employing the DPPH radical scavenging assay indicated that phenolic substitution plays a critical role in activity. Among the series, the vanillin‐derived analogue 5e exhibited the highest inhibition (88.4% at 50 µM), approaching the potency of ascorbic acid (97.6%). Collectively, these results establish a rapid and sustainable synthetic methodology and underscore the potential of this scaffold as a promising antioxidant chemotype. Nevertheless, the biological findings should be regarded as preliminary, warranting further systematic investigation.