Regio- and diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism.

The regio- and diastereoselective synthesis of oxazolidinones via a Pd-catalyzed vicinal C-N/C-Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6 : 1 to >20 : 1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino alcohols.

Unusual Application for Phosphonium Salts and Phosphoranes: Synthesis of Chalcogenides.

A novel strategy for the synthesis of sulfides and selenides from phosphonium salts and thio- or selenesulfonates, commercially available compounds, is described. When phosphoranes were used in the reaction, different products were obtained. The methodology does not require the use of metals, reactive species, or anhydrous conditions to be performed.

Evaluation of Ca Binding Sites in Tacrolimus by Infrared Multiple Photon Dissociation Spectroscopy.

Tacrolimus (TAC) is an efficient immunosuppressant used in organ transplantation procedures. There is an intrinsic correlation between TAC and Ca because of the dependence of its action mechanism on calcium and calcineurin, and the role of ion coordination on TAC identification and quantitation. To depict the Ca binding sites in TAC, this work carried out gas-phase vibrational infrared multiple photon dissociation spectroscopy of [Ca(TAC)] and of three other TAC mimetic molecules (probes 1-3).

Quantification of carvedilol in human plasma by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry: application to bioequivalence study.

A rapid, sensitive and specific method to quantify carvedilol in human plasma using metoprolol as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using a diethyl-ether solvent. After removed and dried the organic phase, the extracts were reconstituted with a fixed volume of acetonitrile-water (50/50; v/v).