Palladium-catalyzed 1,1-difunctionalization of ethylene

The 1,1-difunctionalization of ethylene, with aryl/vinyl/heteroaryl transmetalating agents and vinyl electrophiles, is reported. The reaction is high-yielding under a low pressure of ethylene, and regioselectivity is generally high for the 1,1-disubstituted product. The process is highlighted by the use of heteroaromatic cross-coupling reagents, which have not been competent reaction partners in previously reported efforts.     

A Convenient and Facile Synthesis of Isoxazolyl‐chromeno[4,3,2‐de]pyrimido[4,5‐h][1,6]napthyridinones

The ceric ammonium nitrate‐catalyzed synthesis of (E)‐5‐amino‐N‐(3‐methyl‐5‐styrylisoxazol‐4‐yl)‐2‐arylchromeno[4,3,2‐de][1,6]napthyridin‐4‐carboxamides 5 was simply achieved upon the one‐pot four‐component reaction of isoxazolyl cyanoacetamide 1 with malononitrile 2 , 2‐hydroxy acetophenone 3 , and aromatic aldehydes 4 in ethanol. Compounds 5 on heating with acetic anhydride underwent tandem N‐acetylation and cyclocondensation involving intramolecular cyclization to afford the title compounds (E)‐11‐methyl‐12‐(3‐methyl‐5‐styrylisoxazol‐4‐yl)‐2‐arylchromeno[4,3,2‐de][1,6]napthyridin‐13(12H)‐ones 6 in good yields. The chemical structures have been confirmed by analytical and spectral analyses.     

Simultaneous determination of colchicine and febuxostat in rat plasma: Application in a rat pharmacokinetic study

A selective, sensitive and rapid LC–MS/MS method has been developed and validated as per US Food and Drug Administration regulatory guidelines for the simultaneous quantitation of colchicine and febuxostat in rat plasma. Colchicine and febuxostat were extracted from the rat plasma using 10% tert-butyl methyl ether in ethyl acetate using colchicine-d₆ as an internal standard (IS). The chromatographic separation of colchicine, febuxostat and the IS was achieved using a mobile phase comprising 5 mm ammonium formate and 0.025% formic acid in acetonitrile (20:80, v/v) in isocratic mode on an Eclipse XDB-C₁₈ column. The injection volume and flow rate were 5.0 μl and 0.9 ml/min, respectively. Colchicine and febuxostat were detected by positive electrospray ionization in multiple reaction monitoring mode using transition pairs (Q1 → Q3) of m/z 400.10 → 358.10 and 317.05 → 261.00, respectively. The assay was linear in the ranges of 0.25–254 and 2.60–622 ng/ml for colchicine and febuxostat, respectively. The inter- and intra-day precision values were 0.58–13.0 and 1.03–4.88% for colchicine and febuxostat, respectively. No matrix or carryover effects were observed during the validation. Both analytes were stable on the bench-top, in the autosampler and in storage (freeze–thaw cycles and long-term storage at −80 ° C). A pharmacokinetic study in rats was performed to show the applicability of the validated method.     

Transition-Metal-Free Reverse Reactivity of (2-Alkynyl)-Arylaldimines: Assembly of Functionalized Amino-Indinones

Transition-metal-free regioselective synthesis of functionalized amino-indenones by the reaction of ortho-alkynylaldehydes with a broad range of primary amines by intramolecular cyclization has been described. The designed reaction proceeds through KOH-mediated Prins-type cyclization and DMSO-promoted oxidation of the cyclopent-2-en-1-one system. The proposed mechanism and role of solvent were well supported by control experiments. For the first time, we have disclosed the reverse reactivity of (2-alkynyl)-arylaldimines in a super basic system.     

Chemical modification of L-glutamine to alpha-amino glutarimide on autoclaving facilitates Agrobacterium infection of host and non-host plants: A new use of a known compound

Background

Accidental autoclaving of L-glutamine was found to facilitate the Agrobacterium infection of a non host plant like tea in an earlier study. In the present communication, we elucidate the structural changes in L-glutamine due to autoclaving and also confirm the role of heat transformed L-glutamine in Agrobacterium mediated genetic transformation of host/non host plants.

Results

When autoclaved at 121°C and 15 psi for 20 or 40 min, L-glutamine was structurally modified into 5-oxo proline and 3-amino glutarimide (α-amino glutarimide), respectively. Of the two autoclaved products, only α-amino glutarimide facilitated Agrobacterium infection of a number of resistant to susceptible plants. However, the compound did not have any vir gene inducing property.

Conclusions

We report a one pot autoclave process for the synthesis of 5-oxo proline and α-amino glutarimide from L-glutamine. Xenobiotic detoxifying property of α-amino glutarimide is also proposed.     

Studies on polymerization of vinyl acetate using ylide as an initiator and degradative transfer agent

Polymerization of vinyl acetate initiated by β-picolinium p-chlorophenacylide was carried out at 30, 35, and 40°C, using conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 KJ mol^?1. An average value of k/k_t for the present system was found to be 0.37 × 10^?2. The results are explained in terms of a radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was bimolecular.     

Crystallization behavior of isotactic polypropylene based nanocomposites

The effect of clay dispersion on the crystallization behavior of isotactic polypropylene (iPP)-based nanocomposites is reported. The T _m⁰ of the materials was calculated by the method proposed by Marand, the kinetics of crystallization was evaluated by the Avrami analysis and also the Hoffman-Lauritzen theory of crystallization regimes was applied. Montmorillonite was found to depress T _m⁰, to enhance the rate of crystallization and to ease the chain folding of macromolecules. These effects were magnified if clay was exfoliated, rather than intercalated.     

The influence of a transverse magnetic field on a subnormal glow discharge in air

In subnormal glow discharge under d.c. excitation at different pressure in a varying transverse magnetic field (0 to 30 G) some measurements have been carried out for various initial average tube currents. The voltage across the discharge increases and average tube current and residual current decreases in the magnetic field. With the help of Beckman’s expression [4] for the axial field and the electron density distribution in a transverse magnetic field the observed variation of current and voltage can be satisfactorily explained. The variation of axial electric field with transverse magnetic field can be represented to a fair degree of accuracy by the derived equation. The behaviour of residual current with magnetic field has been observed in these oscillations.