New multicomponent domino reaction on water: highly diastereoselective synthesis of spiro[indoline-3,4′-pyrazolo[3,4-b]pyridines] catalyzed by NaCl

A direct and efficient approach for the preparation of medicinally promising pyrazolopyridinyl spirooxindoles has been developed through a sequential one-pot, three-component reaction of easily available isatin, α-cyanoacetic ester or malononitrile, and 5-amino-3-methylpyrazole catalyzed by sodium chloride in water. Desired products were obtained in high to excellent yields using a simple workup procedure. The product synthesized using α-cyanoacetic ester showed high diastereoselectivity in which the stereochemistry of major diastereomer was confirmed by X-ray diffraction analysis. The present green synthesis shows attractive characteristics such as the use of water as the reaction medium, one pot conditions, short reaction period, easy workup/purification, and reduced waste production, without use of any acid or metal promoters.     

Influence of meta-extended rigid-core,complementary hydrogen bonding and flexible chain on polymorphism in Schiff-base liquid crystals: (4)MeOBD(3)AmBA:nOBAs

ABSTRACT

Schiff-base complementary hydrogen-bonded liquid crystals (HBLC), viz., (4)_MeOBD(3)_AmBA:nOBAs with flexible chain length for n = 3,4,5,6,7,8,9,10,11 and 12 are reported. ¹H; ¹³C-NMR and Infra-Red spectroscopy used to confirm the formation of HBLCs. LC phases and transition temperatures (T_c) determined by polarised optical microscopy (POM) and differential scanning calorimetry (DSC). T_c and enthalpy (?H) determined by DSC also. Odd-Even effect observed at clearing and melting transitions. Influence of Schiff base and Oxygen as bridging atom promote smectic phase abundance. HBLCs exhibit tetra- or penta-phase variance. Maximum (penta) phase variance is exhibited by n = 8 and 12 with long flexible chain. Prevalent abundance of quasi-two-dimensional (2D) LC phases of SmF and SmI is observed. Nematic phase is quenched. Lower (n = 4) and intermediate (n = 6) members exhibited SmB_cryst phase. Predominant occurrence of enantiotropic LC phases is noticed. All members exhibited 3D tilted SmG phase. A-C transition exhibited by intermediate homologues (for n = 7, 8, 9 and 10) is found to be either second order or with very small enthalpy. Phase diagram reveals the abundance of multi-critical points with LC phasesinvolving exotic symmetries. Influence of meta-extended rigid core, complementary HB and flexibility is studied for the LC phase abundance with characteristic structural order. POM and DSC results are discussed in the wake of reports in other achiral calamitic LCs.     

Microwave assisted one-pot synthesis of linear and angular furo chromanone scaffolds and their in vitro antimicrobial activity

Russian Journal of General Chemistry - A new series of linear and angular alkyl substituted furochromanone derivatives have been synthesized in one pot microwave irradiation assisted process from...     

Minimal spin-3/2 dark matter in a simple s-channel model

The European Physical Journal C - Recently in (Eur Phys J C 76:341, 2016), Myung has suggested that the renormalizability of massive conformal gravity is meaningless unless the massive ghost states...     

Naphthobipyrrole‐Derived Sapphyrins: Rational Synthesis,Characterization, Nonlinear Optical Properties,and Excited‐State Dynamics

Two new free‐base β‐octa and hexaalkyl naphthobipyrrole‐derived sapphyrins are reported along with various salts thereof. One of them has substituents at all of its β positions, whereas the pyrrole unit opposite to the bipyrrolic moiety is unsubstituted in the other. The effect of bipyrrole fusion on the structure of sapphyrins was explored. Interestingly, an unprecedented sandwiched supramolecular aqua‐bridged free‐base sapphyrin dimer was also characterized in the solid state. Further, the effect of anions on the third‐order nonlinear optical properties of these sapphyrins were explored in the salt form, along with their detailed excited‐state dynamics by both degenerate and nondegenerate pump–probe studies.     

Extraction and Characterization of Novel Lignocellulosic Fibers From Thespesia Lampas Plant

In this work, the lignocellulosic fibers from the plant Thespesia lampas were extracted and investigated in detail. The prime objective of this work was to study the effect of alkali treatment on the chemical composition, tensile properties, morphological and structural changes, and thermal degradation of Thespesia lampas fibers. Chemical analysis, FT-IR, and ¹³C CP-MAS NMR spectroscopic studies indicated lowering of amorphous hemicellulose content on alkali treatment. Wide-angle X-ray diffraction studies indicated increase in crystallinity of the fibers on alkali treatment. The tensile strength and modulus of the fibers and thermal stability increased on alkali treatment. Scanning electron micrographs revealed roughening of the surface of the fibers due to the removal of the hemicellulose layer on alkali treatment. Tensile properties of Thespesia fibers were compared to those of other important natural fibers, and it was indicated as an alternative suitable source for composite construction.