2‐Substituted Benzo[b]furans from (E)‐1,2‐Dichlorovinyl Ethers and Organoboron Reagents: Scope and Mechanistic Investigations into the One‐Pot Suzuki Coupling/Direct Arylation

Abstract

Abstract2‐Substituted benzo[b]furans can easily be assembled from simple phenols, boronic acids or other organoboron reagents, and trichloroethylene. The overall process requires only two synthetic steps, with the key step being a one‐pot sequential Suzuki cross‐coupling/direct arylation reaction. The method tolerates many useful functional groups and does not require the installation of any other activating functionality. The modular nature of the process permits the rapid synthesis of many analogues using essentially the same chemistry, of particular value in drug development. Results of kinetic isotope effect studies and investigations into the regioselectivity of the process indicate that the direct arylation step most likely does not involve an electrophilic palladation. The most likely mechanism lies somewhere on the continuum between a C–H bond metathesis and an assisted palladation or concerted metallation‐deprotonation pathway.

Zinc Porphyrins with a Pyridine‐Ring‐Anchoring Group for Dye‐Sensitized Solar Cells

“…The desired Wittig reagent was readily prepared from the conveniently substituted ortho ‐hydroxybenzyl alcohol Ia – Ig and PPh 3 ⋅HBr 40–43. The benzofuran structures44–49 were confirmed by 1 H NMR, 13 C NMR, mass spectrometry, and elemental analyses.…”

MAO Inhibitory Activity of 2‐Arylbenzofurans versus 3‐Arylcoumarins: Synthesis, in vitro Study, and Docking Calculations

“…General procedure for the preparation of 2‐phenylbenzofuran : A mixture of 2‐hydroxybenzyltriphenylphosphonium bromide (1.10 mmol) and benzoyl chloride (1.11 mmol) in a mixed solvent (toluene 20 mL and Et 3 N 0.5 mL) was stirred under reflux for 2 h. The precipitate was removed by filtration. The filtrate was concentrated, and the residue was purified by silica gel chromatography (hexane/EtOAc 9:1) to give the desired compounds 1 – 10 44–49…”

On the Interpretation of Deuterium Kinetic Isotope Effects in CH Bond Functionalizations by Transition‐Metal Complexes

“…The first example involves an intramolecular direct arylation of an arene with a vinyl chloride to form benzofuran derivatives. [13] As shown in Scheme 2 a, the reaction of a substrate containing one deuterium in the ortho position gives rise to a k H /k D value of 4.0. Many authors have concluded from similar intramolecular competition experiments that C À H bond cleavage occurs in the rate-or turnoverlimiting step.…”