2.4- Dimethylpyrrole-3,5-dicarboxylic acid, diethyl ester

A mixture of DL-threonine and DL-allothreonine was prepared by the hydrogenation of ethyl diazoacetoacetate over paltinum oxide in 70% ethanol containing sulfuric acid (eq. 9.90). 2,4-Dimethylpyrrole-3,5-dicarboxylic acid diethyl ester was also obtained as a byproduct. 

In the pyrrole series, ester groups a to nitrogen are more readily hydrolyzed by alkali, but those in a (3 position more readily by acid. Thus, in compounds such as diethyl 2,4-dimethylpyrrole-3,5-dicarboxylate (360) either ethoxycarbonyl group may be selectively hydrolyzed and, if desired, subsequently eliminated by decarboxylation. 

---

See also in sourсe #XX -- [ ]

---