Chapter 4

Perbromopyridines

Reza Ranjbar-Karimi and Alireza Poorfreidoni

Abstract

Pentabromopyridine is prepared from 4-hydroxypyridine via two pathways. Pentabromopyridine is less active than pentachloro- and pentafluoropyridine toward nucleophilic attack. Its nucleophilic reaction is affected by the hindrance of the bromine atom. Oxidation and methylation of pentabromopyridine give pentabromopyridine-N-oxide and N-methylbromopyridinium salt. Metal-halogen exchange between pentabromopyridine and n-butyl-lithium or magnesium give tetrabromo-4-pyridyl-lithium and tetrabromo-4-pyridylmagnesium bromide. 2,4,6- tribromo-3,5-difluoropyridine is obtained from the bromination of pentafluoropyridine in the reaction with nucleophiles at the C-F bond. Cross-coupling reactions of 2,4,6- tribromo-3,5-difluoropyridine and 3,5-dibromo-2,6-dichloropyridine produced arylated and alkenylpyridines pyridines.

Total Pages: 219-235 (17)

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