Cu(II)-Catalyzed Synthesis of Naphthalene-1,3-diamine Derivatives from Haloalkynes and Amines

An efficient procedure for the preparation of naphthalene-1,3-diamine derivatives by copper-catalyzed haloalkynes with amines has been reported. The reaction was supposed to proceed through a coupling reaction followed by the dimerization of ynamines

Three-Component, Four-Molecule, Ru-Catalyzed Cascade Reactions of Indoles and Alkyl Bromides with Sodium Nitrite

<div><p></p><p>An operationally simple domino approach for the ruthenium-catalyzed synthesis of (<i>E</i>)-2,3′-bi(3<i>H</i>-indol)-3-one <i>O</i>-alkyl oximes by the region- and stereoselective three-component, four-molecule reactions of indoles with sodium nitrite and alkyl bromides under mild reaction condition in dimethylformamide is described. Remarkably, multiple bonds including C‒C, C=N, and C‒O bonds were conveniently formed in one pot. The reaction is tolerant to air and is atom economical, in accordance with the concept of modern green chemistry.</p></div

Novel oxidative aromatic alkene cleavage with sodium nitrite under mild conditions

<p>We have developed a simple and practical process for the oxidation of aromatic alkene to the corresponding carbonyl compounds using NaNO₂ as an oxidant. The practical utility of this oxidative process has been demonstrated in the gram-scale oxidation of 1-(<i>tert</i>-butyl)-4-vinylbenzene.</p

Metal-Free–Catalyzed Oxidative Trimerization of Indoles Using NaNO₂ to Construct Quaternary Carbon Centers: Synthesis of 2-(1<i>H</i>-Indol-3-yl)-2,3′-biindolin-3-ones

<div><p></p><p>A simple, convenient, and efficient synthesis of 2-(1<i>H</i>-indol-3-yl)-2,3′-biindolin-3-one derivatives via a transition-metal-free-catalyzed oxidative trimeric reaction of indoles has been developed. This transformation may have occurred through a tandem oxidative homocoupling reaction by using NaNO₂ in pyridine as oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C2 position of indoles.</p> </div

High-Performance Wet Adhesion of Wood with Chitosan

Strong adhesion is desirable when using wood with a wide range of moisture contents, but most of the existing adhesives face challenges in bonding wood under high-humidity conditions. Here, we report a simple strategy that involves the one-step dissolution of chitosan powder in acetic acid at room temperature, followed by direct use of the resulting chitosan slurry as an adhesive on dry/wet wood veneers. Mechanical interlocks and hydrogen bonds at cell wall interfaces provided strong adhesion. Moreover, heat treatment induced recrystallization and cross-linking of chitosan chains, resulting in a high cohesion. Meanwhile, heat treatment caused the acetylation reaction between the protonated amino groups (NH3+) of chitosan and acetate groups (CH3COO–) to produce hydrophobic acetyl groups. In addition, we prepared wooden products such as plywood (dry veneers) and wooden straws (wet veneers) using wood veneers with different moisture contents. The tensile shear strengths under 63 °C water and under boiling water of plywood were 1.12 and 0.81 MPa, respectively. The compressive strength of wooden straws is up to 35.32 MPa, which was higher than that of existing commercial straws (such as paper straws, polypropylene straws, and plastic straws). The chitosan wet adhesive showed good water resistance, high bonding strength, environmental degradability, and nontoxicity, thus providing a highly promising alternative to traditional wood composite adhesives