Pyridine carboxamides lithiation

Regioselactive g-metallation of ir-excessive five ring heterocycles is not a novel reaction. Oxazoline and pyridine as well as carboxylate- and carboxamide -substituted heterocycles have been lithiated. From the point of synthetic utility thiophenes have been shown to be useful substrates after careful optimization of reaction conditions furans have been of less utility. 

Scheme 41 Synthesis of spiro-P-lactams via cyclization of lithiated pyridine and quinoline carboxamides...

Clay den et al. [115] have reported the synthesis of spirocyclic p-lactams 176 (Scheme 41) by exo-cyclization of lithiated pyridine and quinoline carboxamides. The reaction of isonicotinamide or chlorinated isonicotinamide 175 with LDA at -40°C with addition of methyl chloroformate led to the formation of spirocyclic p-lactams 176 in good yields. Benzyl chloroformate, benzoyl chloride, methyl triflate can also be used as the effective acylating agents. In these type of reactions, lithiation of /V-benzyl pyridine and quinoline carboxamides to nitrogen provided... 

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