Reactions of 1,7-Naphthyridinones

The most important reaction of tautomeric 1,7-naphthyridinones, halogenolysis, has been covered in Section 17.1. Only a few of the other possible reactions have been reported, as illustrated by the following examples. 

Ethyl 4-amino-2-oxo-1,2-dihydro- (5, R = H) with ethyl bromoacetate gave ethyl 4-amino-1 -ethoxycarbonylmethyl-2-oxo-1,2-dihydro-1,7-naphthyridine-3-carboxylate (5, R = CH2C02Et) (reactants, K2C03, AcEt, reflux, 18 h 66%).725 

Ethyl 6-chloro-8-morpholino-4-oxo-1,4-dihydro- (6, R = H) gave ethyl 5-chloro-1 -ethyl-8-morpholino-4-oxo-1,4-dihydro-1,7-naphthyridine-3-carbox-ylate (6, R = Et) (substrate, K2C03, Me2NCHO, 100°C, 30 min then EtI in, 

Note This reaction amounts to the conversion of a nontautomeric to a tautomeric 1,7-naphthyridinone. 

7-Cyclohexyl-6-pheny limino-6,7-dihydro-l,7-naphthyridine-5,8-quinone (8) with benzonitrile oxide or A -phenylbenzonitrileimide gave the spiro derivatives 9(X = 0) and 9(X = NPh), respectively (reactants, Et3N, solvent 70% and 91%, respectively for fine detail, see original).750 

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