FeCl 3 ·6H 2 O as a green and readily available catalyst for the synthesis of 1-oxo-hexahydroxanthenes by the condensation of salicylaldehydes with 1,3-diketones in aqueous media

Gram-Scale Synthesis of 3-Sulfonyl Flavanones

In this paper, an easy-operational, high-yielding method for the gram-scale synthesis of 3-sulfonyl flavanones is described by a one-pot straightforward POCl₃ mediated intermolecular (5 + 1) annulation of the β-ketosulfones with an o-hydroxyaryl group (dual nucleophile) and arylaldehydes (dual electrophile) in refluxing toluene for 3 h. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via one carbon-oxygen (C-O) and one carbon-carbon (C-C) bond formations.

Activation of lignin by selective oxidation: An emerging strategy for boosting lignin depolymerization to aromatics

Lignin is the most abundant, renewable aromatic resource on earth and holds great potential for the production of value-added chemicals. The efficient valorization of lignin requires to deal with several formidable challenges, especially to prevent it from re-condensation reactions during its depolymerization. Recently, a strategy involving the activation of lignin side chains by selective oxidation of the benzylic alcohol in β-O-4 linkages to facilitate lignin degradation to aromatic monomers has become very popular. This strategy provides great advantages for lignin selective degradation to high yields of aromatics under mild conditions, but requires an additional pre-oxidation step. The purpose of this review is to provide the latest cutting-edge innovations of this novel approach. Various catalytic systems, including those using chemo-catalytic methods, physio-chemo catalytic methods, and/or bio-catalytic methods, for the oxidative activation of lignin side chains are summarized. By analyzing the current situation of lignin depolymerization, certain promising directions are emphasized.

Novel Synthetic Approach for the Access of Functionalised 4H-Chromenes

A simple, efficient and high-yielding one-pot protocol for the synthesis of novel functionalised 4H-chromenes and chromene carboxylic acids has been developed using multi-component domino coupling reactions of anil-like compounds with 1,3-diketones and indole in the presence of formic acid catalyst under solvent-free conditions. The protocol avoids the use of expensive catalysts, toxic solvents and chromatographic separation.