Transition-metal-free C-C σ-bond activation of α-aryl ketones and subsequent Zn-catalyzed intramolecular cyclization: synthesis of tetrasubstituted furans.

A highly atom-economical protocol for the synthesis of tetrasubstituted furans has been developed. This process is realized through the tandem reactions of Cs2CO3 promoted C-C σ-bond activation of α-aryl ketones followed by Zn-catalyzed intramolecular cyclization. This represents the first example for the preparation of tetrasubstituted furans through rearrangement of molecular skeletons and subsequent transformations. Mild reaction conditions and readily accessible starting materials make the protocol attractive in organic synthesis.

Synthesis of cyano-substituted carbazoles via successive C-C/C-H cleavage.

A highly efficient protocol for the synthesis of polysubstituted cyano carbazoles has been developed. This process is realized through the tandem reactions of Cs2CO3 promoted C-C σ-bond activation of α-cyano ketones followed by Fe-catalyzed selective C-H and/or C-C bond activations. Two of the sp2 C-H bonds are functionalized, and two of the C-C σ-bonds are cleaved involving a 1,2-acyl migration during the reaction process.

Improved performance of soy protein adhesive with melamine-urea-formaldehyde prepolymer.

In recent years, soy protein adhesive, as an environmentally friendly bio-based adhesive, has attracted extensive attention. In this study, in order to ameliorate the bonding quality of soy protein isolate (SPI) adhesive, the melamine-urea-formaldehyde prepolymer (MUFP) was synthesized, and different amounts of it were introduced into the SPI adhesive as a cross-linking agent. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analyze (TGA), and scanning electron microscopy (SEM) were used to analysis the mechanism of modification. The results of plywood test indicated that the wet bonding strength of the adhesives was first increased and then decreased with an increase in the amount of MUFP additive. FT-IR, TGA, and SEM tests suggested that the introduction of MUFP could promote the establishment of a cross-linking structure in the cured adhesive layer to improve the bonding quality of adhesives, but presence of excessive MUFP could introduce hydrophilic groups and adversely affect water resistance.