Regioselective Synthesis of Polysubstituted Haloallenones from γ ‐Hydroxyl Ynones via TMSBr/TMSCl‐Promoted Halogenative Rearrangement

ABSTRACT An efficient protocol for the synthesis of structurally novel polysubstituted allenones from γ ‐hydroxyl ynones has been developed using trimethylsilyl bromide (TMSBr) and trimethylsilyl chloride (TMSCl) as promoters. The transformation proceeds under mild conditions with high regioselectivity, delivering a wide range of bromo‐ and chloro‐allenones in up to 92% yield. This atom‐economical method features broad functional group tolerance and excellent scalability, as demonstrated by a gram‐scale synthesis with quantitative yield. The synthetic utility was further demonstrated by a metal‐free cycloisomerization to halogenated furans.