A rapid and sensitive method for determination of methylene-diphosphonate in rat bone using liquid chromatography-mass spectrometry.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of methylene-diphosphonate (MDP) in rat bone. This method employed derivatization of MDP and allowed rapid and sensitive quantification of MDP in rat shin bone. The analyte was extracted from the bone tissues with phosphoric acid and derivatized to MDP tetramethyl phosphonate using trimethylsilyl diazomethane (TMS-DAM).

Asymmetric Total Synthesis of (+)-21-epi-Eburnamonine Via a Photocatalytic Radical Cascade Reaction.

An asymmetric total synthesis of (+)-21-epi-eburnamonine has been achieved. Key features of the synthesis include a visible-light photocatalytic intra-/intramolecular radical cascade reaction to assemble the tetracyclic ABCD ring system, and a highly diastereoselective Johnson-Claisen rearrangement to establish the C20 all-carbon quaternary stereocenter.