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Carboxylate Catalyzed Isomerization of β,γ-Unsaturated N-Acetylcysteamine Thioesters.

ABSTRACT: We demonstrate herein the capacity of simple carboxylate salts - tetrametylammonium and tetramethylguanidinium pivalate - to act as catalysts in the isomerization of β,γ-unsaturated thioesters to α,β-unsaturated thioesters. The carboxylate catalysts gave reaction rates comparable to those obtained with DBU, but with fewer side reactions. The reaction exhibits a normal secondary kinetic isotope effect (k_1H /k_1D =1.065±0.026) with a β,γ-deuterated substrate. Computational analysis of the mechanism provides a similar value (k_1H /k_1D =1.05) with a mechanism where γ-reprotonation of the enolate intermediate is rate determining.

SUBMITTER: Riuttamaki S

PROVIDER: S-EPMC9541288 | biostudies-literature | 2022 Aug

REPOSITORIES: biostudies-literature

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Carboxylate Catalyzed Isomerization of β,γ-Unsaturated N-Acetylcysteamine Thioesters.

Riuttamäki Saara S Laczkó Gergely G Madarász Ádám Á Földes Tamás T Pápai Imre I Bannykh Anton A Pihko Petri M PM

Chemistry (Weinheim an der Bergstrasse, Germany) 20220620 45

We demonstrate herein the capacity of simple carboxylate salts - tetrametylammonium and tetramethylguanidinium pivalate - to act as catalysts in the isomerization of β,γ-unsaturated thioesters to α,β-unsaturated thioesters. The carboxylate catalysts gave reaction rates comparable to those obtained with DBU, but with fewer side reactions. The reaction exhibits a normal secondary kinetic isotope effect (k1H /k1D =1.065±0.026) with a β,γ-deuterated substrate. Computational ana ...[more]

PMID: 35604200

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