Mechanism of hydrolysis of coumaran-2-ones

David M. Heathcote; Gareth A. De Boos; John H. Atherton; Michael I. Page

doi:10.1039/a707946j

Mechanism of hydrolysis of coumaran-2-ones

David M. Heathcote, Gareth A. De Boos, John H. Atherton, Michael I. Page

School of Applied Sciences

AstraZeneca

Research output: Contribution to journal › Article › peer-review

14 Citations (Scopus)

Abstract

The hydrolysis of coumaran-2-one and 5-substituted 3-phenylcoumaran-2-ones is preceded by a pre-equilibrium involving the formation of an enolate anion at high pH. The pK_a of 3-phenylcoumaran-2-one is 8.39 in water at 25°C and the 3-phenyl substituent increases the carbon acidity by 10⁴. However, despite this ready carbanion formation, the conventional addition-elimination mechanism for hydrolysis of 3-phenylcoumaran-2-ones is confirmed by a solvent kinetic isotope effect of 0.63 and a Brønsted β_1g of -0.6. This is compatible with rate limiting formation of a tetrahedral intermediate.

Original language	English
Pages (from-to)	535-540
Number of pages	6
Journal	Journal of the Chemical Society. Perkin Transactions 2
Issue number	3
DOIs	https://doi.org/10.1039/a707946j
Publication status	Published - Mar 1998

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title = "Mechanism of hydrolysis of coumaran-2-ones",

abstract = "The hydrolysis of coumaran-2-one and 5-substituted 3-phenylcoumaran-2-ones is preceded by a pre-equilibrium involving the formation of an enolate anion at high pH. The pKa of 3-phenylcoumaran-2-one is 8.39 in water at 25°C and the 3-phenyl substituent increases the carbon acidity by 104. However, despite this ready carbanion formation, the conventional addition-elimination mechanism for hydrolysis of 3-phenylcoumaran-2-ones is confirmed by a solvent kinetic isotope effect of 0.63 and a Br{\o}nsted β1g of -0.6. This is compatible with rate limiting formation of a tetrahedral intermediate.",

author = "Heathcote, \{David M.\} and \{De Boos\}, \{Gareth A.\} and Atherton, \{John H.\} and Page, \{Michael I.\}",

year = "1998",

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doi = "10.1039/a707946j",

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pages = "535--540",

journal = "Journal of the Chemical Society. Perkin Transactions 2",

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T1 - Mechanism of hydrolysis of coumaran-2-ones

AU - Heathcote, David M.

AU - De Boos, Gareth A.

AU - Atherton, John H.

AU - Page, Michael I.

PY - 1998/3

Y1 - 1998/3

N2 - The hydrolysis of coumaran-2-one and 5-substituted 3-phenylcoumaran-2-ones is preceded by a pre-equilibrium involving the formation of an enolate anion at high pH. The pKa of 3-phenylcoumaran-2-one is 8.39 in water at 25°C and the 3-phenyl substituent increases the carbon acidity by 104. However, despite this ready carbanion formation, the conventional addition-elimination mechanism for hydrolysis of 3-phenylcoumaran-2-ones is confirmed by a solvent kinetic isotope effect of 0.63 and a Brønsted β1g of -0.6. This is compatible with rate limiting formation of a tetrahedral intermediate.

AB - The hydrolysis of coumaran-2-one and 5-substituted 3-phenylcoumaran-2-ones is preceded by a pre-equilibrium involving the formation of an enolate anion at high pH. The pKa of 3-phenylcoumaran-2-one is 8.39 in water at 25°C and the 3-phenyl substituent increases the carbon acidity by 104. However, despite this ready carbanion formation, the conventional addition-elimination mechanism for hydrolysis of 3-phenylcoumaran-2-ones is confirmed by a solvent kinetic isotope effect of 0.63 and a Brønsted β1g of -0.6. This is compatible with rate limiting formation of a tetrahedral intermediate.

UR - https://www.scopus.com/pages/publications/0039374908

U2 - 10.1039/a707946j

DO - 10.1039/a707946j

M3 - Article

AN - SCOPUS:0039374908

SN - 0300-9580

SP - 535

EP - 540

JO - Journal of the Chemical Society. Perkin Transactions 2

JF - Journal of the Chemical Society. Perkin Transactions 2

IS - 3

ER -

Mechanism of hydrolysis of coumaran-2-ones

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