Glutaric anhydride, hydrolysis

All the syntheses of tricyclic ketones in Scheme 8 described so far have been carried out from comparatively poorly accessible meta-substituted anisoles. Consequently, the possibility of using themore accessible para-substituted anisoles as starting materials offered considerable interest [219]. The acylation of anisole (82) with glutaric anhydride, esterification, the Stobbe reaction, and hydrolysis led to the triacid (87). 

Glutarimides may be regarded as oxidized piperidines, and many drugs containing this moiety are sedatives and anticonvulsants. A spiro derivative, alonimid (105) is such a sedative-hypnotic agent. It can be prepared by K t-butoxide catalyzed biscyano-ethylation of phenylacetonitrile, leading to 101. Alkaline hydrolysis produces tricarboxylic acid 102 which is smoothly Converted to the glutaric acid anhydride (103) with acetic anhydride. Friedel-Crafts... 

A. N. Dey (174) has described an independent synthesis of the alkaloids. Michael condensation of ethyl 7-ethoxy- or 7-phenoxy-crotonate (LI, R = OEt, R = Et or Ph) with ethyl malonate or cyan-acetate, followed by ethylation and hydrolysis, furnished a mixture of the two racemic forms of the glutaric acid, LII, which were separated by virtue of their different ease of anhydride formation. On treatment with hydrobromic acid, they gave rise to dl-homopilopic acid and dl-homo-isopilopic acid (LIII, R = OH), respectively. Corresponding methyl ketones (LIII, R = Me) were obtained by a similar synthesis from... 

The same synthetic approach was used for the preparation of cyclic anhydrides [39- 3]. It was known before that succinic and glutaric acid form cyclic anhydrides which do not polymerize (see Formula 3.1, bottom). HiU and Carothers studied the reactions of higher dicarboxylic acids with acetyl chloride or acetic anhydride. In aU cases, polymeric anhydrides were obtained which were supposed to possess mixed anhydride end groups containing acetyl residues. The sensitivity to hydrolysis alcoholysis and phenolysis prevented exact molar mass measurements. However, a reliable distinction from monomeric cyclic anhydrides was achieved by reaction with aniline, because cyclic anhydrides can only yield one reaction product. When the polymeric anhydrides were heated to 150 °C in vacuum they degraded almost completely by back-biting . In this way 10 new cyclic anhydrides were isolated. These cyclic anhydrides underwent rapid polymerization in contact with traces of moisture. 

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