Conversion of Cyclohexanones to Alkyl Aryl Ethers by Using a Pd/C-Ethylene System

Synthesis of 2-(Pyridin-2-yl)phenols and 2-(Pyridin-2-yl)anilines

Herein, we report a new synthetic strategy for 2-(pyridin-2-yl)phenols and 2-(pyridin-2-yl)anilines catalyzed by a Pd/C-ethylene system. The starting materials, 2-(pyridin-2-yl)cyclohexan-1-ones, can be easily prepared by the reaction of substituted pyridine N-oxide and cyclohexanones. The most useful feature of this method is that both 2-(pyridin-2-yl)phenols and 2-(pyridin-2-yl)anilines are easily synthesized independently using the same compound as a starting material, simply by adding or not adding a nitrogen source.

Discovery and bioinspired total syntheses of unprecedented sesquiterpenoid dimers unveiled bifurcating [4 + 2] cycloaddition and target differentiation of enantiomers

[4 + 2] cycloaddition has led to diverse polycyclic chiral architectures, serving as novel sources for organic synthesis and biological exploration. Here, an unprecedented class of cadinane sesquiterpene [4 + 2] dimers, henryinins A-E (1-5), with a unique 6/6/6/6/6-fused pentacyclic system, were isolated from Schisandra henryi. The divergent total syntheses of compounds 1-5 and their enantiomers (6-10) were concisely accomplished in eight linear steps using a protection-free approach. Mechanistic studies illustrated the origin of selectivity in the key [4 + 2] cycloaddition as well as the inhibition of reaction pathway bifurcation via desymmetrization. The chemical proteomics results showed that a pair of enantiomers shared common targets (PRDX5 C100 and BLMH C73) and had unique targets (USP45 C588 for 4 and COG7 C419 for 9). This work provides experimental evidence for the discovery of unprecedented cadinane dimers from selective Diels-Alder reaction and a powerful strategy to explore the biological properties of natural products.

Aluminium-catalysed synthesis of aryl enol ethers from phenols and dimethyl ketals

We report an environmentally friendly, aluminium-catalysed, halide- and transition metal-free method for the synthesis of aryl enol ethers from phenols and dimethyl ketals that involves ketal exchange driven by the removal of methanol. The obtained aryl enol ethers were transformed into the corresponding diaryl ethers by Pd/C-catalysed dehydrogenation or DDQ oxidation.

Reduced Phenalenyl in Catalytic Dehalogenative Deuteration and Hydrodehalogenation of Aryl Halides

Dehalogenative deuteration reactions are generally performed through metal-mediated processes. This report demonstrates a mild protocol for hydrodehalogenation and dehalogenative deuteration of aryl/heteroaryl halides (39 examples) using a reduced odd alternant hydrocarbon phenalenyl under transition metal-free conditions and has been employed successfully for the incorporation of deuterium in various biologically active compounds. The combined approach of experimental and theoretical studies revealed a single electron transfer-based mechanism.

Synthesis of Substituted Anilines from Cyclohexanones Using Pd/C-Ethylene System and Its Application to Indole Synthesis

The synthesis of anilines and indoles from cyclohexanones using a Pd/C-ethylene system is reported. A simple combination of NH₄OAc and K₂CO₃ under nonaerobic conditions was found to be the most suitable to perform this reaction. Hydrogen transfer between cyclohexanone and ethylene generates the desired products. The reaction tolerates a variety of substitutions on the starting cyclohexanones.

Catalytic dehydrogenative aromatization of cyclohexanones and cyclohexenones

Prompted by the scant attention paid by published literature reviews to the comprehensive catalytic dehydrogenative aromatization of cyclohexa(e)nones, this review describes recent methods developed to-date involving transition-metal-catalyzed oxidative aromatization and metal-free strategies for the transformation of cyclohexa(e)nones to substituted phenols.