Diastereoselective Ortho Lithiation of Phosphinimidic Amides: A Multinuclear Magnetic Resonance and Computational Study

Crystal, Solution, and Computational Study of the Structure of Ortho-Lithium N,N-Diisopropyl-P,P-Diphenylphosphinothioic Amide

The first crystal structure of an ortho-lithium phosphinothioic amide complexed with tetramethylethylenediamine 12 is reported. The complex consists of a spirane in which the spiro-lithium is N,N- and C,S-chelated by the diamine and organophosphorus ligands, respectively. The analogous ortho anion 14 obtained by Sn(IV)/Li transmetallation in THF has also been synthesized. Nuclear magnetic resonance study of both anions showed that they exist as monomers in solution and are involved in dynamic processes including the restricted rotation around the P-N bond. 14 is converted at room temperature by nucleophilic cyclization to the dearomatized anion 15, which evolves after a few hours to the benzophosphindole sulfide 16. Density functional theory calculations supported the aggregation state in solution and were used to explore the conformational space of anion 12, the mechanism of ortho-lithiation directed by P(X)-N (X=O, S) groups, and the mechanism of formation of 15.

In vivo pharmacokinetic studies and intracellular delivery of methotrexate by means of glycine-tethered PLGA-based polymeric micelles

Methotrexate (MTX) is a widely used drug for the management of various kinds of cancers. However, numerous challenges are associated with MTX like poor aqueous solubility, dose-dependent side effects and poor-bioavailability. With an aim to explore the potential benefits in drug delivery of MTX, it was intended to fabricate glycine-PLGA-based polymeric micelles. Glycine was chemically linked to PLGA and the linkage was confirmed by FT-IR, and NMR-Spectroscopy. The developed polymeric micelles offered substantial loading to MTX with a pH-dependent drug release profile. The drug was released maximally at the cancer cell pH vis-à-vis blood plasma pH. The cytotoxicity of drug against MDA-MB-231 cell lines was enhanced by approx. 100% and the confocal laser scanning microscopy confirmed the localization of dye-tagged nanocarriers in the interiors of cancer cells. The bioavailable fraction of the drug was increased by approx. 4-folds, whereas elimination half-life was enhanced by around two-folds in Wistar rats. The novel approach offers a biodegradable and promising carrier for the better delivery of anticancer agents with immense promises of efficacy enhancement, improved delivery and better pharmacokinetic profile.