Ultra-Fast Halogen Dance Enabled by Catalytic KHMDS

Catalytic potassium hexamethyldisilazide (KHMDS) accelerates a bromine–metal exchange rather than potassium tert-butoxide (KOtBu), which is stoichiometrically used for the Lochmann–Schlosser base, a combination of nBuLi and KOtBu. Loading of 1.0–10 mol% of KHMDS drastically facilitated successive bromine–metal exchanges consisting of a halogen dance reaction within 1 min to introduce various electrophiles on bromopyridine, imidazole, thiophene, furan, and benzene derivatives with the bromo group translocated from the original position. A dual catalytic cycle is proposed to explain the ultra-fast bromine transfer showing the significant potential to realize new catalytic reactions of aryllithium species using KHMDS.