Unusual sterically controlled regioselective lithiation of 3-bromo-5-(4,4′-dimethyl)oxazolinylpyridine.: Straightforward access to highly substituted nicotinic acid derivatives

Lithiation of 5-bromonicotinic acid protected as secondary or tertiary amide as well as(4,4'- dimethyl) oxazoline with lithium amides is reported. The unusual C-2 and C-4 regioselective lithiation of 3-bromo-5-(4,4'-dimethyl)oxazolinylpyridine using LTMP versus LDA was observed, providing a new route to substituted nicotinic acid scaffolds. The methodology was applied to the synthesis of novel C-4 and C-6 arylated 5-bromonicotinic acids.