Pyridines 4-lithio-3-bromo

Bromo substituents in the 6- and 6 -positions of 2,2 -bipyridines are particularly reactive, being readily converted to amino,cyano, ° al-koxyl, hydrazino, chloro, and hydrogen groups and by way of the corresponding lithio derivatives to carboxyl, methyl, aldehyde or alkylcarbonyl, and other groupings. 6,6 -Dibromo-2,2 -bi-pyridine also reacts with the disodium derivatives of polyethylene glycols to give crown ethers akin to 100, and 6,6 -bis(chloromethyl)-2,2 -bi-pyridine " and the derived 6,6 -bis(mercaptomethyl)-2,2 -bipyridine... 

The bromine group in 4-bromo-5-methoxy-2-trifluoromethyl-l,10-phenanthroline has been replaced by lithium with w-butyllithium and the lithio derivative reacted with pyridine 2-aldehyde.215... 

Direct lithiation of l,2,3-triazolo[l,5-a]pyridines occurs with ease, at C-7, subsequent reaction with electrophiles being unexceptional, for example conversion into the 7-bromo-derivative then allows nucleophiles to be introduced via displacement of halide, thus providing, overall, a route to 2,6-disubstituted pyridines." However, lithiation in tetrahydrofuran as solvent leads to formation of a 7,7-linked dimer. The 7-lithio compound is also formed by cleavage of the 7-N,N-diethylcarboxamide with n-butyllithium. ... 

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