Determination of isoflavones in rat serum using liquid chromatography-tandem mass spectrometry with a highly efficient core-shell column.

Consumption and nutritional supplementation of soy and soy-based products have been linked to health benefits such as lower cholesterol and triglyceride levels, and decreased incidence of cardiovascular disease and diabetes. In this study, we have developed a sensitive, specific, and robust method using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for determination of serum isoflavones. A new highly efficient pentafluorophenyl phase core-shell column was first used to separate all isoflavones within 3 min, a separation time which is comparable to ultra-pressure liquid chromatography (UPLC) and micro-HPLC.

Analysis of the critical step in catalytic carbodiimide transformation: proton transfer from amines, phosphines, and alkynes to guanidinates, phosphaguanidinates, and propiolamidinates with Li and Al catalysts.

While lithium amides supported by tetramethylethylenediamine (TMEDA) are efficient catalysts in the synthesis of substituted guanidines via the guanylation of an amine with carbodiimide, as well as the guanylation of phosphines and conversion of alkynes into propiolamidines, aluminum amides are only efficient catalysts for the guanylation of amides. Density functional theory (DFT) calculations were used to explain this difference in activity. The origin of this behavior is apparent in the critical step where a proton is transferred from the substrate to a metal guanidinate.

Amidolithium and amidoaluminum catalyzed synthesis of substituted guanidines: an interplay of DFT modeling and experiment.

The synthesis of substituted guanidines is of significant interest for their use as versatile ligands and for the synthesis of bioactive molecules. Lithium amides supported by tetramethylethylenediamine have recently been shown to catalyze the guanylation of amines with carbodiimide. In this report, density functional theory (DFT) calculations are used to provide insight into the mechanism of this transformation.

Atom efficient cyclotrimerization of dimethylcyanamide catalyzed by aluminium amide: a combined experimental and theoretical investigation.

A novel method for the cyclotrimerization of dimethylcyanamide to form hexamethylmelamine has been developed using an aluminium amide catalyst; detailed DFT modelling of the catalytic cycle supports a triple insertion, nucleophilic ring closure, deinsertion mechanism.