Catalysis of the cyclohexadienone-phenol rearrangement by a Lewis-acidic clay system

Iodine-Catalyzed Claisen-Rearrangements of Allyl Aryl Ethers and Subsequent Iodocyclizations

Iodine can be considered as the simplest halogen-bond donor. Previous investigations have revealed its remarkable catalytic effect in various reactions. The catalytic activity of iodine can often even compete with that of traditional Lewis acids. So far, iodine was typically used to activate carbonyl derivatives like Michael acceptors. We now demonstrate that iodine can also be used to activate allyl aryl ethers in Claisen rearrangements. The formed ortho-allylic phenols rapidly undergo iodocyclizations to afford dihydrobenzofurans, which are important building blocks for medicinal applications. A comparison with different catalysts further highlights the potential of iodine catalysis for this reaction. Computational and mechanistic investigations provide deeper insights into the underlying non-covalent interactions and their role for the catalysis.

Spirocarbocycle Synthesis from Chloromethylarenes via Transition-Metal-Catalyzed Allylative Dearomatization and Ring Closure Metathesis

A strategy for the synthesis of spirocarbocycles by using chloromethyl arenes as starting materials is described in this paper. The palladium-catalyzed allylative dearomatization and the subsequent ruthenium-catalyzed ring closure metathesis proceeded smoothly under mild conditions to produce the corresponding spirocarbocycle products with moderate to high yields. Benzene-ring-, naphthalene-ring-, and anthracene-ring-containing substrates can be easily transformed into spirocarbocycles by using the proposed method.

Synthesis of 3,3′-arylmethylidenebis-4-hydroxycoumarin derivatives catalysed by KF-montmorillonite

3,3′-Arylmethylidenebis-4-hydroxycoumarins derivatives have been synthesised in good yields by the Michael addition reaction of aromatic aldehydes with 4-hydroxycoumarin in DMF catalysed by KF-montmorillonite.

Re2O7catalyzed dienone-phenol rearrangement

The dienone-phenol rearrangement of 4,4-disubstituted cyclohexadienones to multi-substituted phenols is achieved by employing Re₂O₇as the catalyst.

K10 montmorillonite clays as environmentally benign catalysts for organic reactions

This perspective summarizes the catalytic activity of K10 montmorillonite as a multifunctional catalyst for organic reactions.

Synthesis of 2-Amino-4-Aryl-5-Oxo-4,5-Dihydropyrano[3,2-c] Chromene Derivatives Catalysed by KF-Montmorillonite

A series of 2-amino-4-aryl-5-oxo-4,5-dihydropyrano[3,2- c]chromene derivatives has been synthesised by the reaction of 4-hydroxycoumarin and substituted cinnamonitriles catalysed by KF-montmorillonite. The structures were characterised by IR and 1H NMR spectroscopic data and confirmed by X-ray diffraction analysis.

Synthesis of 3-Methyl-6-Amino-5-Cyano-4-Aryl-1-Phenyl-1,4-Dihydropyrano [2,3-c]Pyrazole Catalysed by KF-Montmorillonite

The reaction of substituted arylidenemalononitriles and 3-methyl-1-phenyl-2-pyrazolin- 5-one in DMF in the presence of KF-montmorillonite provides a rapid synthesis of 3-methyl-6-amino-5-cyano-4-aryl-1-phenyl-1,4-dihydro-pyrano[2,3-c]pyrazole derivatives.

Chemical Reactions on Clays

Layer aluminosilicates catalyze reactions in numerous ways. They stabilize high-energy intermediates. They can store energy in their lattice structures and can release it in the form of chemical energy. They can catalyze redox reactions and can serve as photocatalytic devices. They often exhibit high surface acidity. Organic reactions that are catalyzed by the agency of days are reviewed. The role of clays in prebiotic chemistry is also examined.