1- -3,5-dinitro-2-pyridone, reaction

Nitroenamines and related compounds have been used for synthesis of a variety of heterocyclic compounds. Rajappahas summarized the chemistry of nitroenamines (see Section 4.2).140 Ariga and coworkers have developed the synthesis of heterocycles based on the reaction of nitropyridones or nitropyrimidinone with nucleophiles. For example, 2-substituted 3-nitro-pyridines are obtained by the reaction of l-methyl-3,5-dinitro-2-pyridones with ketones in the presence of ammonia (Eq. 10.82).141... 

The reaction of l-(2-pyridyl)-3,5-dinitro-2-pyridone 14 with ethyl sodio acetoacetate or diethyl sodio acetone-dicarboxylate gave a mixture of N-(2-pyridyl)nitroacetamide 15, phenol derivatives 16, and a low yield of 2-oxo-2,5-dihydropyrido[1,2-b [ 1,2,4]triazine 4-oxide 17 (79TL1393). The mechanism of the reaction is shown in Scheme 5. 

In order to clarify the reaction mechanism, 6-deuterio-labeled 3,5-dinitro-l-methyl-2-pyridone (87, 1 mmol) was prepared and heated with cyclohexanone (2 mmol) and ammonia (10 mmol). A mixture of 2-deuterio- (88) and 4-deuterio-3-nitro-5,6,7,8-tetrahydroquinoline (89) was obtained in the ratio 58 42 (Scheme III.49). 

Ref 6) this same compd described in CA (Ref 3) as yel prisms (from MeOH), mp 102-3° is obviously incorrectly identified. It was prepd by reaction of 3,5"dinitro-2(lH) pyridone (pale yel crysts, mp 175°) with PC15 P0C13 heated at 120°... 

Nitration of 2-pyridone, originally thought to give mainly 3-nitro-2-pyridone (47) together with some 3,5-dinitro-2-pyridone (48) and a trace of the 5-nitro derivative (49),123 was later shown to give a mixture of 47 and 48.124 Similarly, reaction of 6-methyl-2-pyridone with nitric acid in glacial acetic acid gave the product of nitration at C-3 (50).125 This preferential ortho-nitration is in marked contrast to... 

The action of hydrazine or hydroxylamine on certain other nitropyrimidine systems leads to 4-nitropyrazoles and 4-nitrooxazoles [549], When 1,5-disubstituted 4-nitro-6-pyridazinone derivatives are heated in an alkaline medium the derivatives of 4-nitropyrazole are formed with high yields. 1-Substituted 4-nitropyrazole-5-carboxyiic acids [550, 551] or 1-substituted 4-nitropyrazoles [552-554] can be obtained, depending on the conditions. Another promising method of synthesis has been opened up for the production of 4-nitropyrazole derivatives. 4-Nitropyrazole is obtained with a high yield in the reaction of 3,5-dinitro-2-pyridone with hydrazine [555] (Scheme 99). 

Two more synthetic methods have been described, but are of limited scope. A linearly fused benzologue (148) was synthesized from 2,4-dinitro-iV-piperidinoaniline (147) by treatment with acid (Equation (25)). A benzimidazole derivative was also formed in this reaction probably via tertiary amino effect. Cope elimination, cyclization, and a hydrolytic step <77JCS(P1)478>. Ring transformation of 3,5-dinitro-l-(2-pyridyl)-2-pyridone with sodio acetoacetate lead also to the formation of this ring system, but in poor yield <79TL1393>. 

The gas-phase equilibrium between 2-hydroxypyridine and 2-pyridone favours the hydroxy-form, but in the equilibrium between 2-hydroxypyridine iV-oxide and N-hydroxy-2-pyridone, the major tautomer is the hydroxy-pyridone. Bicyclic adducts between 2-pyridones and dimethyl acetylene-dicarboxylate, unobtainable at atmospheric pressure, have been obtained at 10—15 kbar. A novel route to iV-hydroxy-2-pyridone involves the trimethyl-silylation of 2-pyridone followed by oxidation of the resulting 2-(trimethyl-silyloxy)pyridine with the DMF complex of molybdenum pentoxide. p-Nitro-phenols (45) and nitro-acetamides (46) are formed from the reaction of 3,5-dinitro-2-pyridones (43) with the sodium salts of /3-keto-esters (44) (Scheme 20). ... 

Alkoxypyridines rearrange at elevated temperatures to A -alkyl.4-pyndones. Isomerizations of this kind are catalyzed by acids and alkyl halides. Spinner and White, however, have prepared 4-methoxypyridine from 4-chloropyridine and sodium methoxide in 86% yield through temperature control and by neutralization of the reaction mixture with solid carbon dioxide. 2-(3,5-Dinitro-2-pyridyl)pyridinium chloride (XII-367), formed from 3,5-di-nitro-2-chloropyridine and pyridine in benzene or ether, is readily hydrolyzed in an alkaline medium to 3,5-dinitro-2-pyridone. ... 

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