The Hydrolysis of Ethyl 1-Methyl-2,4-cyclopentadiene-1-carboxylate by Nonenzymatic and Enzymatic Methods. Carbon-Carbon vs. Carbon-Oxygen Bond Cleavage

✍ Scribed by Ulrich Burger; Dominique Erne-Zellweger; Christa Mayerl

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: German
• Weight: 455 KB
• Volume: 70
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19870700311

✦ Synopsis

The title ester 5 is shown to undergo C-C bond cleavage under the conditions of basic ester hydrolysis (KOH/EtOH) with formation of potassium ethyl carbonate (6) and the tautomeric methylcyclopentadienes 7 and 8. In contrast, porcine liver esterase (PLE, EC 3.1.1.1 j cleanly hydrolyses 5 to give the isolable l-methyl-2,4-cyclopentadiene-I-carboxylic acid (13). The latter undergoes thermal dimerization with conservation of the geminalsubstitution pattern. The configuration of the Diels-Alder adduct 17 is ascertained by it photochemical transformation into bishomocubane dicarboxylic acid 12, easily distinguished by its C, symmetry. Under the conditions of acid-catalyzed hydrolysis, dimerization of ester 5 and polymerization prevail, unless low acid concentration is used. The dimer 9 of 5 has one ester function that is reluctant to undergo basic hydrolysis.