Bakhat Ali

Functionalization of protected tyrosine via Sonogashira reaction: synthesis of 3-(1,2,3-triazolyl)-tyrosine

Abstract1,2,3-Triazol tyrosines were synthesized from tyrosine alkynes that were in turn prepared via Sonogashira cross-coupling reaction. The tyrosine alkynes were subjected to click-chemistry reaction conditions leading to the corresponding 3-(1,2,3-triazolyl)-tyrosines in yields ranging from moderate to good.

Synthesis, spectral characterization and computed optical analysis of potent triazole based compounds

Biologically active triazole Schiff base ligand (L) and metal complexes [Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] are reported herein. The ligand acted as tridentate and coordinated towards metallic ions via azomethine-N, triazolic-N moiety and deprotonated-O of phenyl substituents in an octahedral manner. These compounds were characterized by physical, spectral and analytical analysis. The synthesized ligand and metal complexes were screened for antibacterial pathogens against Chromohalobacter salexigens, Chromohalobacter israelensi, Halomonas halofila and Halomonas salina, antifungal bioassay against Aspergillus niger and Aspergellus flavin, antioxidant (DPPH, phosphomolybdate) and also for enzyme inhibition [butyrylcholinesterase (BChE) and acetylcholinesterase (AChE)] studies. The results of these activities indicated the ligand to possess potential activity which significantly increased upon chelation. Moreover, vibrational bands, frontier molecular orbitals (FMOs) and natural bond analysis (NBO) of ligand (1) were carried out through density functional theory (DFT) with B3lYP/6-311++G (d,p) approach. While, UV-Vis analysis was performed by time dependent TD-DFT with B3lYP/6-311++G (d,p) method. NBO analysis revealed that investigated compound (L) contains enormous molecular stability owing to hyper conjugative interactions. Theoretical spectroscopic findings showed good agreement to experimental spectroscopic data. Global reactivity descriptors were calculated using the energies of FMOs which indicated compound (L) might be bioactive. These parameters confirmed the charge transfer phenomenon and reasonable correspondence with experimental bioactivity results.

Crystal structure of 1-benzyl-2-hy­droxy-5-oxopyrrolidin-3-yl acetate

In the title compound, C13H15NO4, the oxopyrrolidin-3-yl ring has an envelope conformation, with the C atom bearing the acetate group being the flap. The acetate and phenyl groups are inclined with respect to the central ring, forming dihedral angles of 50.20 (12) and 87.40 (9)°, respectively, with the least-squares plane through the ring. The dihedral angle between the acetate group and the phenyl ring is 63.22 (8)°, indicating a twisted conformation in the molecule. In the crystal, supramolecular chains along the b axis are formed by (hydroxy)O—H⋯O(ring carbonyl) hydrogen bonds. The chains are consolidated into the three-dimensional architecture by C—H⋯O interactions.

New Sphingolipids from Abutilon pakistanicum

Pakistamides A and B (1and 2, respectively), two new sphingolipids, have been isolated from the AcOEt-soluble sub-fraction of the MeOH extract of the whole plant of Abutilon pakistanicum. Their structures were assigned by 1H and 13C NMR spectra, and by DEPT and COSY, NOESY, HMQC, HMBC, EI-MS, and FAB-MS experiments. Graphical Abstract New Sphingolipids from Abutilon pakistanicum

Addition of Amino Acids to oxopyrrolidin compounds

INTRODUCTION Amino acids are building blocks of proteins. G. J. Mulder first discovered protein in 1838. He described that proteins are most vital among ever known organic substances, without which life cannot sustain. Amino acids are very many in number but among them 20 are found in human body. Our group has been working in oxopyrrolidin compounds [1, 2]. So, addition of amino acids to oxopyrrolidin has created great interest. For nucleophilic addition of nitrogen of amino acids as nucleophiles, we have generated N-acyliminium ions. BF3 generates Nacyliminium ions, which play an important role in the reactive intermediates for the nucleophilic addition to form nitrogen heterocycles. For this purpose, we have added more than 10 amino aicds successfully. Here protection of amino acids, formation of oxopyrrolidin compounds, generation of Nacyliminium ions, addition of amino acids and deprotection of amino acids is presented.