Remarkable catalytic activity of silica nanoparticle in the bis-Michael addition of active methylene compounds to conjugated alkenes

We have demonstrated the remarkable catalytic activity of silica nanoparticles (NPs) in the unusual bis-Michael addition of active methylene compounds to conjugated alkenes at room temperature. The catalyst silica NPs were reused up to seven runs without appreciable loss of catalytic activity.     

Catalysis by Lithium Perchlorate Enables Double-Conjugate Addition of Electron-Deficient Maleimides to 2-Aminopyridines and 2-Aminothiazoles

Lithium perchlorate has been found to catalyze the conjugate addition of maleimides with 2-aminopyridines and 2-aminothiazoles. The reaction proceeds under mild conditions leading to the corresponding double adducts in good yields. A plausible mechanism of this reaction has been proposed.

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A simple and highly efficient procedure for construction of quaternary carbons centers by tributylphosphine catalyzed bis-Michael addition

The tributylphosphine-catalyzed bis-Michael addition reaction of various kinds of α,β-unsaturated carbonyl compounds with active methylenes is described. This is a convenient and rapid method for generating quaternary carbons centers and useful procedure for the synthesis of branched core and highly substituted trans cyclohexanones. All the reactions were completed in 60 min and afford the corresponding products in excellent yields.     

Synthesis, spectral and structural characterization of dinuclear rhodium (II) complexes of the anticonvulsant drug valproate with theophylline and caffeine

The dinuclear complex tetra(μ-valproato) dirhodium(II), Rh₂(valp)₄ (1), and its bis-adducts with theophylline, Rh₂(valp)₄(ThH)₂ (4), or caffeine, Rh₂(valp)₄(Caf)₂ (5), have been synthesized and characterized by elemental analysis, IR, UV-Vis, magnetic moment, ¹H and ¹³C NMR spectroscopic techniques. Spectral data for the complexes are consistent with a dinuclear structure as found for rhodium (II) tetracarboxylate adducts. Theophylline and caffeine bases in complexes 4 and 5, respectively, are axially coordinated to rhodium (II) atoms through the sterically hindered N(9) site. This is confirmed by X-ray crystal structure analyses of complexes 4 and 5.