P. Nesvadba, P. Rzadek, G. Rist
2001
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0
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Journal
Collection of Czechoslovak Chemical Communications
Abstract
(3,5-Di- tert -butyl-4-oxocyclohexa-2,5-dienylidene)acetic acid 1a underwent on heating a new cyclodimerization reaction affording a 1 : 1 mixture of the racemic cis - and trans -isomeric lactone-acids 2 . The decisive structure elucidation of 2 was carried out after its mild esterification with diazomethane and separation of the racemic isomeric methyl esters 3a and 3b . The attempted esterification of 2 with methanol and sulfuric acid gave only the methyl diarylacetate 4 . In contrast to 1a , which contains the carboxylic acid functionality no cyclodimerization was observed with the corresponding methyl ester 1b or nitrile 1c .