Asymmetric Diels-Alder reactions with a chiral spirodione, (6S, 7S, 10R)-7-Isopropyl-10-methyl-1-oxaspiro[5.5]undec-3-ene-2,5-dione

The synthesis of the title spirodione, a new class of auxiliary based chiral synthon, using (−)-menthone having a unique carbon-carbon bond is described. Diels-Alder reactions were carried out with variety of dienes using the title auxiliary as a chiral dienophile in the presence of diethyl aluminium chloride as Lewis acid catalyst to afford the cycloadduct with good diastereoselectivity. The configurations of the chiral synthon and cycloadducts were determined by X-ray crystallography. Methodology for detachment of the chiral auxiliary from the cycloadducts has been developed.     

New pimarane diterpenes and other antimycobacterial metabolites from Anisochilus verticillatus

Phytochemical investigation of the acetone extract of the aerial parts of Anisochilus verticillatus afforded a new 8,9-secopimarane diterpene (1), two new isopimarane diterpenes (2, 3) and the known ursolic acid (4), α-amyrin (5), β-amyrin (6), stigmast-5-en-3-one (7) and hydroxychavicol (8). Structures of the new compounds were elucidated with the help of 1D and 2D nuclear magnetic resonance spectroscopic data, and single crystal X-ray crystallography of compound 3. Compounds 2 and 8 inhibited Mycobacterium tuberculosis H37Ra with an IC₅₀ of 11.3 (IC₉₀ of 20.0 μg/mL) and 12.5 μg/mL, respectively. Correspondingly, molecular docking studies with Extra Precision Glide revealed a correlation between score and biological activity for these compounds to describe the molecular basis for the most significant SAR results.     

Mass spectrometry-based glycoprofiling of biopharmaceuticals by using an automated data processing tool: SimGlycan®

The therapeutic and immunological properties of biopharmaceuticals are governed by the glycoforms contained in them. Thus, bioinformatics tools capable of performing comprehensive characterization of glycans are significantly important to the biopharma industry. The primary structural elucidation of glycans using mass spectrometry is tricky and tedious in terms of spectral interpretation. In this study, the biosimilars of a therapeutic monoclonal antibody and an Fc-fusion protein with moderate and heavy glycosylation, respectively, were employed as representative biopharmaceuticals for released glycan analysis using liquid chromatography–tandem mass spectrometry instead of conventional mass spectrometry-based analysis. SimGlycan® is a software with proven ability to process tandem MS data for released glycans could identify eight additional glycoforms in Fc-fusion protein biosimilar, which were not detected during mass spectrometry analysis of released glycans or glyco-peptide mapping of the same molecule. Thus, liquid chromatography–tandem mass spectrometry analysis of released glycans not only complements conventional liquid chromatography–mass spectrometry-based glycan profiling but can also identify additional glycan structures that may otherwise be omitted during conventional liquid chromatography–tandem mass spectrometry based analysis of mAbs. The mass spectrometry data processing tools, such as PMI Byos™, SimGlycan^®, etc., can display pivotal analytical capabilities in automated liquid chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry-based glycan analysis workflows, especially for high-throughput structural characterization of glycoforms in biopharmaceuticals.     

Synthesis of 1,2,3-triazole and 1,2,3,4-tetrazole-fused glycosides and nucleosides by an intramolecular 1,3-dipolar cycloaddition reaction

Various 1,2,3-triazole and 1,2,3,4-tetrazole fused multi-cyclic compounds were synthesized from carbohydrate derived azido-alkyne and azido-cyanide substrates. The acid sensitive 1,2-O-isopropylidene group of the furanosyl sugar was utilized for diversification to glycosides and nucleosides under Fischer glycosidation and Vorbruggen's conditions, respectively.     

Synthesis and characterization of the new mixed-metal,mixed-chalcogen clusters Fe2 M(CO)10(μ3-S)(μ3-Te) (M=W,Mo). crystal structure of Fe2W(CO)10(μ3-S)(μ3-Te)

The new clusters Fe₂ M(CO)₁₀(µ₃-S)(µ₃-Te), I (M=W) and 2 (M=Mo) have been isolated from the room temperature reaction of Fe₂(CO)₆(µ-STe) andM(CO)₅(THF) (M=W, Mo), respectively. Compounds1 and2 have been characterized by IR, 125 Te NMR spectroscopy, and elemental analysis. The structure of compound1 has been established by X-ray crystallography. It belongs to the triclinic space groupP witha=6.844(2) Å,b=9.397(2) Å,c=13.681(10) Å, =81.64(2)°,=81360r,=812(2)°,V=861.2(3) ų,Z=2,D _e =2.835 g cm^–3. Full-matrix least-squares refinement of1 converged to R=0.043, andR _w .=0.115. The structure consists of a Fe₂ WSTe square pyramid and the W atom occupies the apical site of the square pyramid.     

Stereoselective synthesis of (+)-isoindolo-β-carboline

Starting from homophthalic anhydride and (S)-tryptophan, the stereoselective synthesis of (+)-isoindolo-β-carboline has been described via the corresponding homophthalimide, its chemoselective oxidative ring contraction, and the intramolecular dehydrative ring closure followed by a geometry-specific demethoxycarbonylation.