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 γreprotonation of the enolate intermediate is rate determining.

A mild catalytic variant of the aldol reaction between ethyl diazoacetate and aldehydes is described using a combination of N,O-bis(trimethylsilyl)acetamide and catalytic tetramethylammonium pivalate as catalyst. The reaction proceeds rapidly at ambient temperature to afford the O-silylated aldol products in good to excellent yield, and the acetamide byproducts can be removed by simple filtration.

A mild catalytic variant of the aldol reaction between ethyl diazoacetate and aldehydes is described using a combination of N,O-bis(trimethylsilyl)acetamide and catalytic tetramethylammonium pivalate as catalyst. The reaction proceeds rapidly at ambient temperature to afford the O-silylated aldol products in good to excellent yield, and the acetamide byproducts can be removed by simple filtration.

We demonstrate herein the capacity of simple carboxylate salts – tetrametylammo-nium 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 analysis of the mechanism provides a similar value (k1H/k1D = 1.05) with a mechanism where -reprotonation of the enolate intermediate is rate determining.We demonstrate herein the capacity of simple carboxylate salts – tetrametylammo-nium 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 deuterated substrate. Computational analysis of the mechanism provides a similar value (k1H/k1D = 1.05) with a mechanism where γ-reprotonation of the enolate intermediate is rate determining.