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Theoretical Study on the Epimerization of Azlactone Rings: Keto-Enol Tautomerism or Base-Mediated Racemization?

ABSTRACT: Azlactones are versatile heterocycles employed in a diversity of transformations; the main drawback of these cycles consists in the epimerization of the ?-carbonyl stereocenter during its preparation. We hereby present a theoretical study to explain how the racemization occurs. Two hypotheses were investigated: the keto-enol tautomerism and the base-mediated racemization, through an enolate intermediate. The results showed that the latter is consistent with the experimental data and can spontaneously occur at room temperature. The same pathway was evaluated for 2-alcoxy azlactone, showing a slower epimerization ratio, consistent with the literature data.

SUBMITTER: de Castro PP

PROVIDER: S-EPMC6641619 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Theoretical Study on the Epimerization of Azlactone Rings: Keto-Enol Tautomerism or Base-Mediated Racemization?

de Castro Pedro P PP Batista Gabriel M F GMF Dos Santos Hélio F HF Amarante Giovanni W GW

ACS omega 20180326 3

Azlactones are versatile heterocycles employed in a diversity of transformations; the main drawback of these cycles consists in the epimerization of the α-carbonyl stereocenter during its preparation. We hereby present a theoretical study to explain how the racemization occurs. Two hypotheses were investigated: the keto-enol tautomerism and the base-mediated racemization, through an enolate intermediate. The results showed that the latter is consistent with the experimental data and can spontane ...[more]

PMID: 31458601

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Theoretical Study on the Epimerization of Azlactone Rings: Keto-Enol Tautomerism or Base-Mediated Racemization?

Publications

Theoretical Study on the Epimerization of Azlactone Rings: Keto-Enol Tautomerism or Base-Mediated Racemization?

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