• Archives of Pharmacal Research
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• v.16 no.2
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• pp.152-154
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• 1993

By using N-bromophthalimide (NBP) as halonium ion source for the Hofmann rearrangement, a series of primary amide could be ocnverted to the corresponding cabamate in excellent yields. So NBP was throught to be very effective and practical halonium ion source for the Hofmann rearrangement.

• Bulletin of the Korean Chemical Society
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• v.26 no.8
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• pp.1190-1196
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• 2005

Halopyrroles, N-substituted 2-halopyrroles were prepared by halogenation of N-substituted pyrroles with NBS, NCS, or surfuryl chloride. N-Substituted 3-halopyrroles were synthesized by acid-catalyzed thermal and photochemical isomerization reactions of N-substituted 2-halopyrroles. Both the thermal and photochemical reactions were acid-catalyzed. For the acid-catalyzed isomerization, a mechanism of [1,3] bromine shift followed by deprotonation is operated. For the acid-catalyzed photoisomerization, an excited triplet state of 2-protonated N-benzyl-2-halopyrrole produces an intermediate N-substituted pyrrole complex with halonium ion which is equilibrated with N-substituted pyrrole plus halonium ion, and then the halonium ion newly adds to 3-position of N-substituted pyrrole followed by deprotonation to afford N-benzyl-3-halopyrrole.