23985-59-3Relevant articles and documents
MNBA-mediated β-lactone formation: Mechanistic studies and application for the asymmetric total synthesis of tetrahydrolipstatin
Shiina, Isamu,Umezaki, Yuma,Kuroda, Nobutaka,Iizumi, Takashi,Nagai, Shunsuke,Katoh, Takashi
experimental part, p. 4885 - 4901 (2012/07/30)
Various β-lactones were prepared from β-hydroxycarboxylic acids by intramolecular dehydration condensation using MNBA, an effective coupling reagent, along with a nucleophilic catalyst. The transition state that provides the desired 4-membered ring model system is disclosed by density functional theory (DFT) calculations, and the structural features of the transition form are discussed. This method was successfully applied to the asymmetric total synthesis of tetrahydrolipstatin (THL), an antiobestic drug used in clinical treatment to inhibit the activity of pancreatic lipase.
Olefin Synthesis by Vanadium(V)-Induced Oxidative Decarboxylation-Deoxygenation of 3-Hydroxy Carboxylic Acids
Meier, Ingrid K.,Schwartz, Jeffrey
, p. 5619 - 5624 (2007/10/02)
Oxidative decarboxylation of 3-hydroxy carboxylic acids can be effected with various V(V) complexes.This process likely yields an intermediate 1,4-metalla diradical. β-elimination from this intermediate gives olefin and regenerates V(V), likely as VO2Cl.Thus, although the overall process involves no net change in oxidation state for vanadium, the decarboxylation process is oxidatively induced.Intramolecular trapping of the intermediate yields glycolate and then C-C cleavage products, and skeletal rearrangement gives ketonic products.Qualitatively, rates for oxidative decarboxylation of the acids and the stereospecificity of formation of olefinic products depend on the electron-withdrawing ability of groups attached to vanadium.Methodology is described for the preparation of tri- and tetrasubstituted olefins in high yield from appropriate 3-hydroxy carboxylic acid precursors.
Preparation of trialkylsilyl ethers
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, (2008/06/13)
In an improved catalytic process for preparing trialkylsilyl ethers from trialkylsilyl compounds and carbonyl group-containing compounds, the improvement consisting of using an organic or inorganic bifluoride (HF2?) as the catalyst.
