Synchronized Aromaticity Enables Syntheses of 2,4-Cyclohexadienones via [3 + 2]/[3,3]-Cascade Reaction

A [3+2]-dipolar cycloaddition of 2,6-disubstituted aryloxyallenes and 4-nitrobenzenesulfonyl azide (NsN₃) followed by a Claisen rearrangement driven by synchronized aromaticity affords novel 2,4-cyclohexadienones. The starting materials are easily synthesized, and the reaction proceeds under mild conditions in one pot and avoids the use of a significantly more dangerous azide that was used in prior work. The dearomatized products can then be functionalized via Diels-Alder cycloadditions, enabling the rapid generation of molecular complexity from planar arenes.