Enantioseparation of DPP-4 Inhibitors on Immobilized Crown Ether-Based Chiral Stationary Phase

A group of DPP-4 inhibitors such as alogliptin, linagliptin and saxagliptin were selected for enantioseparation for this study. Crown ether columns contain a chiral crown ether ring as a chiral selector is suitable for the compounds having primary amino groups. Since the selected compounds contain free amino groups, a crown ether column was selected for enantiomeric separation of dipeptidyl peptidase-4 inhibitors. Dipeptidyl peptidase-4 inhibitors are a class of oral hypoglycemics that block dipeptidyl peptidase-4 enzyme and can be used to treat diabetes mellitus type 2. A sensitive HPLC method was developed to separate the enantiomers of each dipeptidyl peptidase-4 inhibitor. Effects of various parameters such as type of solvents, selection of additives, effect of pH and column temperature on chromatographic results were studied. The optimal conditions for the chiral separation of dipeptidyl peptidase-4 inhibitors without any derivatization were investigated.     

Design,Synthesis, and Anti-Proliferative Activity of Some New Quinoxaline Containing 1,2,4-Thiadiazoles Amide Hybrids

Russian Journal of General Chemistry - A series of new quinoxaline-1,2,4-thiadiazoles amide hybrids has been synthesized and evaluated for their anti-proliferative activity on four different human...     

X‐Ray Characterization of an Electron Donor–Acceptor Complex that Drives the Photochemical Alkylation of Indoles

A metal‐free, photochemical strategy for the direct alkylation of indoles was developed. The reaction, which occurs at ambient temperature, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, generated upon association of substituted 1H‐indoles with electron‐accepting benzyl and phenacyl bromides. Significant mechanistic insights are provided by the X‐ray single‐crystal analysis of an EDA complex relevant to the photoalkylation and the determination of the quantum yield (Φ) of the process.     

Liquid chromatographic separation and thermodynamic investigation of stereoisomers of darunavir on Chiralpak AD‐Hcolumn

Liquid chromatographic separation of stereoisomers of darunavir on Chiralpak AD‐H, a column containing the stationary phase coated with amylose tris(3,5‐dimethylphenylcarbamate) as a chiral selector, was studied under normal‐phase conditions at different temperatures between 20 and 50°C. The effect of quality and quantity of different polar organic modifiers viz: methanol, ethanol, 1‐propanol, and 2‐propanol in the mobile phase as well as column temperature on retention, separation, and resolution was investigated and optimized. The optimum separation was accomplished using a mobile phase composed of n‐hexane/ethanol/diethyl amine (80:20:0.1 v/v/v) at 40°C. Apparent thermodynamic parameters ΔH⁰ and ΔS* were derived from the Van't Hoff plots (lnk′ versus 1/T) and used to explain the strength of interactions between the stereoisomers and amylose tris(3,5‐dimethylphenylcarbamate) coated chiral stationary phase.     

Total Synthesis of (E/Z) des-Hydroxy Triticone A and B

The first total synthesis of des-hydroxy triticone A and B was achieved in 12 steps. The highly chemoselective, base mediated iodolactamization of olefins with N-OMe amide motif is a key highlight of the synthesis.