benzofurans and quinone-methide

A PPh

Topics: Benzofurans; Chlorides; Indolequinones; Molecular Structure

Topics: Benzofurans; Catalysis; Indolequinones

The intramolecular cycloaddition of o-quinone methides (o-QMs) with a carbonyl group has been envisaged and executed successfully in the context of constructing the complex and rare [6,6,6,6]-tetracyclic core found in the integrastatins, epicoccolide A, and epicocconigrone A. These transient o-QMs were generated easily from the oxidative dearomatization of the corresponding C2-(aryl)benzofuran by employing Oxone in acetone-water at rt. The subsequent cycloaddition with the carbonyl (or conjugated olefin) present on the C2-aryl group was spontaneous.

Topics: Benzofurans; Cycloaddition Reaction; Heterocyclic Compounds, Bridged-Ring; Indolequinones; Molecular Structure; Oxidation-Reduction; Stereoisomerism; Sulfuric Acids

Persistent free radicals have become indispensable in the synthesis of organic materials through living radical polymerization. However, examples of their use in the synthesis of small molecules are rare. Here, we report the application of persistent radical and quinone methide intermediates to the synthesis of the resveratrol tetramers nepalensinol B and vateriaphenol C. The spontaneous cleavage and reconstitution of exceptionally weak carbon-carbon bonds has enabled a stereoconvergent oxidative dimerization of racemic materials in a transformation that likely coincides with the biogenesis of these natural products. The efficient synthesis of higher-order oligomers of resveratrol will facilitate the biological studies necessary to elucidate their mechanism(s) of action.

Topics: Benzofurans; Biological Products; Carbon; Dimerization; Indolequinones; Oxidation-Reduction; Resorcinols; Resveratrol; Stilbenes

A new method is presented for the regioselective one-pot synthesis of 3-substituted 2,3-dihydrobenzofurans from 2-bromo-1-{2-[(triisopropylsilyl)oxy]phenyl}ethyl nitrate by fluoride-induced desilylation leading to o-quinone methide generation, Michael addition of different C, N, O, and S nucleophiles, and intramolecular 5-exo-tet elimination of a bromide anion. The method has potential synthetic applications in drug discovery.

Topics: Benzofurans; Combinatorial Chemistry Techniques; Indolequinones; Molecular Structure; Organosilicon Compounds; Stereoisomerism

A novel and efficient method for the generation of o-quinone methide intermediates was developed from the readily available 2-tosylalkylphenols under the mild basic conditions, and their reactions with sulfur ylides were investigated for the stereoselective synthesis of trans-2,3-dihydrobenzofurans.

Topics: Benzofurans; Indolequinones; Molecular Structure; Phenols

Topics: Acylation; Anions; Azo Compounds; Benzofurans; Indolequinones; Ketones; Molecular Structure; Sulfhydryl Compounds