NAPHTHYRIDINECARBOXYLIC ACIDS AND RELATED DERIVATIVES

A few such compounds have been made by primary syntheses, covered in Section 29.1 for example, lV-(ethoxycarbonylmethyl)-3-(p-fluorobenzoyl)-(V-methyl-4-pyridinecarboxamide (55) underwent cyclization to ethyl 4-p-fluorophe-ny 1-2-methyl-1-oxo-l,2-dihydro-2,6-naphthyridine-3-carboxylate (56, R = Et) (substrate, diazabicycloundecene, PhMe, reflux 38%).1199 This ester underwent saponification to 4-p-fluorophenyl-2-methyl-1 -oxo-1,2-dihydro-2,6-naphthyridine-3-carboxyhc acid (56, R = H) (NaOH, EtOH, H20, THF, reflux 95%) and subsequent conversion (via the unisolated carbonyl chloride) into /V- 3,5-bis 

Other reactions of such carboxylic derivatives appear to be of marginal chemical 

Although a substantial number of papers are devoted, at least in part, to 2, 7-naphthyridines, the spread of information is quite unbalanced in favor of primary syntheses. Accordingly, the 2,7-naphthyridine system will be covered in a single chapter. Several reviews of naphthyridine chemistry include material on the 2,7-system.49 50 53 61 265 407 456 1357 1430 1432 The original system name, copyrin/ copyrine,13 cf 39,40 is still used occasionally. 

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