Pyridine Pyridineacetic acids

Pyridines with an a- or y-carboxymethyl group (e.g. 685) undergo facile decarboxylation by a zwitterion mechanism (685 — 688) somewhat similar to that for the decarboxylation of 3-keto acids (cf. Section 3.2.3.1.1). Carboxymethylpyridines often decarboxylate spontaneously on formation thus, hydrolysis of (689) gives (690). The corresponding 2- and 4-pyridone and 2- and 4-pyrone acids are somewhat more stable, e.g. (691) decarboxylates at 170°C. 3-Pyridineacetic acid shows no pronounced tendency to decarboxylate. 

Indenes, from pyridineacetic acid derivatives, 488-490 Indenones, from pyridine hydroxy compounds, 368 Indigoidin, 854 from 3-amino-2,6-pyridinediol, 854... 

Pyridineacetic acids, conversion to pyridine side-chain carboxylic acids, 422-420 dihydro, oxidation with O2,... 

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