Synchronized Aromaticity Enables Facile 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 significantly more dangerous azides used in prior work. The dearomatized products can then be functionalized via Diels-Alder cycloadditions, enabling rapid generation of molecular complexity from planar arenes.