The Journal of Organic Chemistry最新文献

The Cp*Rh-catalyzed C–H arylation of indoles with arylsilanes is developed. This C–H activation transformation allows for the Rh-catalyzed indole C₂ arylation to overcome the limitations of requiring strong directing group assistance and high-temperature conditions, achieving a room-temperature transformation driven by a weak directing group. Cp*Rh/MeOH catalytic media are considered a key factor enabling this transformation to occur under mild conditions, and experimental studies and theoretical calculations were performed to rationalize the reaction mechanisms and the influence of methanol as a solvent in promoting the reaction.

A highly efficient palladium-catalyzed domino coupling reaction of ortho-iodoaryl allene with sodium sulfonates under mild conditions is described. This novel method provides a practical protocol to access diverse indole- and benzofuran-containing sulfones by simultaneous construction of C(sp²)–C(sp²) bond and a C(sp³)–S bonds in one pot. The salient features of this transformation include simple operations, broad substrate scope, and good functional group tolerance.

Isoindolones constitute a dominant structural class in synthetic and medicinal chemistry. In this research, an electrochemical reaction involving 2-alkynylbenzamides, inorganic sulfites, and alcohols was first established to provide sulfonyl ester-substituted 3-hydroxyisoindolinone derivatives in moderate to good yields with excellent functional group tolerance. When bulky aryl-substituted 2-alkynylbenzamides are utilized as substrates, sulfonyl ester-substituted 3-alkylideneisoindolinones can be selectively generated with good chemoselectivity. Alkoxysulfonyl radicals derived from the anodic oxidation of inorganic sulfite with alcohols are involved in this transformation.

Herein, we report an atom-economical, one-pot, four-component, diastereoselective double-annulation reaction to construct polyfused pyrroloquinolines. This reaction highlights the cyclization of in situ-formed Povarov adducts with allenoates for the first time.

Sulfonylhydrazones have been proven to be versatile synthetic intermediates in a panel of transformations. However, radical sulfonylation with sulfonylhydrazone as sulfonyl radical source is relatively rare. Here, we found that sulfonylhydrazone can serve as a new sulfonyl radical precursor to couple various partners such as arylacetic acids, ene–yne–ketones, and para-quinone methides under copper catalysis and microwave irradiation. The reactions of sulfonyl radicals have been successively developed to enable the divergent synthesis of C(sp³)-sulfonyl bonds. In addition, when alkynes and alkenes are used as radical receptors, this method can also promote the formation of C(sp²)-sulfonyl bonds. This finding suggests that sulfonylhydrazone could be regarded as a potentially useful sulfonyl radical in sulfone synthesis.

A novel and efficient 6π 1,5-diaza-electrocyclization of readily available isatin, α-ketoester derived hydrazones with α,β-unsaturated ketoesters, ketones, and aldehydes has been developed. A series of functionalized pyrazoles bearing an oxindole unit were easily afforded by this tool with good yields and high functional group tolerance under mild conditions. Importantly, the obtained pyrazole could be further converted to 3-pyrazolecarboxylic acid with a quaternary carbon stereocenter.

The first general synthesis of 2-halomethyleneoxetanes, realized by the reaction of 2-methyleneoxetanes with N-halosuccinimides (NXS), is reported. The relative diastereoselectivities of the transformations were dependent on the halogen of NXS, while alternative reaction outcomes were influenced by substituents on the oxetane. Quantum mechanical calculations and molecular dynamics simulations exploring the basis of the observed diastereoselectivities are described. These highly strained heterocycles underwent standard cross-coupling reactions, demonstrating their utility as synthetic intermediates.

The preparation of a focused library of chiral 2-amido and 2-amido-1-phenyl-1,3-dienes from a range of chiral oxazolidinones using palladium-catalysis is reported. This palladium-catalyzed carbon–nitrogen bond-forming reaction provides the corresponding chiral amido-dienes in moderate to excellent yields (12 examples, up to 97%). The resulting chiral amido-dienes are employed as novel dienes in Diels–Alder (DA) reactions (58 examples, up to 93:7 dr, up to 70% yield). A range of chiral cyclic ketones were accessed upon hydrolysis, affording products with high levels of enantioselectivity (up to 92% ee, up to 81% yield).

We show the first examples of one-pot tandem sulfamoylation/aza-Michael reactions for the preparation of oxathiazinane dioxide heterocycles from linear alkenyl alcohol precursors. Our optimized protocols are tolerant of a variety of functional groups and provide products that are amenable for further transformations. The reactions scale well, and no special precautions are required to exclude air or ambient moisture.

2-Amino-4-arylazulene derivatives were prepared from 8-aryl-2H-cyclohepta[b]furan-2-ones, which were converted into 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones through a several step process. The reaction of 8-aryl-2H-cyclohepta[b]furan-2-ones bearing an ester group at the 3-position with malononitrile in the presence of triethylamine afforded 2-amino-4-arylazulenes. The prepared 2-amino-4-arylazulenes were converted to the corresponding 2-chloro derivatives by the Sandmeyer reaction, which were subsequently transformed into 2,4-diarylazulenes by Suzuki–Miyaura coupling with various aryl boronic acids. 2,4-Diarylazulenes underwent intramolecular cyclization between aryl and cyano groups by Brønsted acid to give 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones. UV/vis spectral analysis revealed that 6-aryl-7H-naphth[3,2,1-cd]azulen-7-one with a N,N-dimethylaminophenyl group at the 6-position exhibited a broad and strong absorption band in the visible region due to intramolecular charge transfer. Furthermore, 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones exhibited halochromism in 30% CF₃CO₂H/CH₂Cl₂. Although fluorescence was not observed in solution, 8-aryl-2H-cyclohepta[b]furan-2-ones with an ester function were found to fluoresce in the solid state. 6-Aryl-7H-naphth[3,2,1-cd]azulen-7-ones also displayed spectral changes with good reversibility under the electrochemical redox conditions.