Transition Metal-Free Synthesis of meta-Bromo- and meta-Trifluoromethylanilines from Cyclopentanones by a Cascade Reaction

Anilines are key constituents in biologically active compounds and often obtained from transition metal-catalyzed coupling of an aryl halide with an amine. In this work, we report a transition metal-free method for the synthesis of meta-bromo- and meta-trifluoromethylanilines starting from 3-tribromomethylcyclopentanone or 3-(2-bromo-2-chloro-1,1,1-trifluoroethyl)cyclopentanone, respectively. The scope of the transformation is shown by application of primary, secondary and aromatic amines. The reaction proceeds in acceptable to high yields (20–81 %), and allows for the synthesis of anilines with substitution patterns otherwise difficult to access.     

Discrete lattice simulation of transient motions in elastic and viscoelastic composites

Discrete viscous lattices are studied in order to mathematically simulate the propagation of general disturbances in semi-infinite, elastic and viscoelastic periodic composites. Integral transform techniques are employed to derive exact and approximate solutions for the cases in which viscosity is introduced to the elastic lattice by adding dash pots in both series and parallel with the springs connecting adjacent particles. Solutions for the continuum models (for vanishing lattice spacings) are also derived either directly or as special cases. It is demonstrated that the effect of the periodic discretization in these systems induces oscillation about the continuum solutions. Comparison of the exact and approximate results shows excellent correlation, particularly near the wave front.     

Magnetic Field Effects on Spacetime Around?a?Magnetized Spherical Star

We investigate the effects of magnetic field on the background spacetime of a spherically symmetric relativistic star. Using the general relativistic Maxwell equations coupled to the Einstein field equations for the gravitational field, it is shown that not only the backreaction of the spacetime modifies the magnetic field of the star, but also the magnetic field of the star molds the spacetime in its vicinity. The part played by the poloidal as well as the toroidal components of the magnetic field on the exterior spacetime are investigated.     

Experimental and Molecular Mechanical Studies of Complexation of Some 2H- and 3H- Indole Derivatives with Aqueous β-Cyclodextrin

Phase solubility diagrams (PSDs) at 25 ^∘C and molecular mechanical (MM) modeling were used to study the aqueous complexation of some 2H- and 3H-indole derivatives with β-cyclodextrin (β-CD). Among the 3H-indole derivatives investigated in this work, indole-3H-butyric acid forms the most stable 1:1 complex of the B _s -type PSD, whereas shorter chain derivatives form soluble 1:1 complexes (A _L -type PSDs) with their stability increasing as the chain length increases. Indole-2 carboxylic acid forms highly stable 1:1 and 1:2 complexes, with the lower-order complex reaching saturation first (B _s -type PSD). MM modeling indicates that the stability of the complex is highly correlated with the flexibility of the 3H-indole hydrocarbon chain, which yields a better geometrical fit within the β-CD cavity resulting from different hydrophilic interactions. These interactions are represented in the H-bonding of the carboxyl group with the primary hydroxyl group network that is situated at the narrow rim of the cavity, and also by a favorable interaction of the aromatic ring with the hydroxyl group network at the other rim.     

Diels-alder reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine with some 1-morpholinocycloalkenes

The reactions of 3, 6-diphenyl-1, 2, 4, 5-tetrazine 1 and 3, 6-di(2-pyridyl)-1, 2, 4, 5-tetrazine 2 with the enamines 3a-d derived from morpholine and the 5-,6-,7- and 8-membered cyclic ketones have been investigated. A number of pyridazine derivatives 4–7 most of which are new have been reported. Moreover, a novel procedure for the aromatization of pyridazines 5a-d to the corresponding pyridazine 7b-d via oxidative elimination using hydrogen peroxide is described. The structures of products 4–7 were confirmed by spectral methods and elemental analysis.     

Microbial transformation of dehydroepiandrosterone

Transformation of dehydroepiandrosterone (DHEA) (1) was carried out by a plant pathogen Rhizopus stolonifer, which resulted in the production of seven metabolites. These metabolites were identified as 3beta,17beta-dihydroxyanandrost-5-ene (2), 3beta,17beta-dihydroxyandrost-4ene (3), 17beta-hydroxyandrost-4-ene-3-one (4), 3beta,11-dihydroxyandrost-4-ene-17-one (5), 3beta,7alpha-dihydroandrost-5-ene-17-one (6), 3A,7alpha,17beta-trihydroxyandrost-5-ene (7) and 11beta-hydroxyandrost-4,6-diene-3,17-dione (8). The structures of the transformed products were determined by the spectroscopic techniques.