Glutaconic acid anhydrides

Glutaconic acid derivatives have been used extensively for the synthesis of 2,6-pyridinediols however, there has been relatively little interest in these compounds during the past ten years. /S-(p-Methoxypheriyl)glutaconic acid (Xn-6) and methylamine orbenzylaminegiveN-methyl-or/V-benzyl 6 hydroxy 4-(p-methoxyphenyI)-2-pyridone (Xn-7). )3-Methylglutaconic anhydride and... 

NaOH or 60% HjSOg —> glutaconic acid. CH3COCI in the cold —> 2-aoetoxyglutarlc anhydride. 

The isomeric 6-hydroxy-2-pyrone (glutaconic anhydride) and its 4-methyl analog (47) react similarly with aryldiazonium salts and on hydrolysis with dilute alkali or acid the hydrazones (48) are transformed into l-aryl-6-oxo-l,6-dihydro-3-pyridazinecarboxylic acids or their 4-methyl analogs (49) in variable yields (28-74%). 

Needles from HgO. MLp. 95°. Sol. H2O, EtOH. Spar. sol. EtgO. Vacuum dist.—> vinylacetic acid + glutwonic add + glutaconic anhydride. HI at 180° —> glutmc acid. 

AIGI3 added portionwise during ca. 30 min. with water-cooling at 15-20° to a well stirred soln. of -(2-methoxy-4-methylphenyl)glutaconic anhydride and anisole in nitrobenzene, stirred 4 hrs. at room temp. 4-(2-methoxy-4-methylphenyl)-6-anisyl-2-pyrone (Y 78%) dissolved in boiling alcohol, aq. NaOH added, and refluxed 15 min. 3-(2-methoxy-4-methylphenyl)-5-anisyl-5-oxo-2-pentenoic acid (Y 72%). F. e. s. J. J. Nerurkar et al., J. Org. Ghem. 25, 1491 (1960). 

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