Asian Journal of Organic Chemistry最新文献

Spirocycles are important structural motifs, found in natural and pharmaceutical compounds, which have attracted considerable interest in modern drug discovery research. Herein, we describe the development of a visible light‐mediated ipso‐cyclization of amino acid derivatives with N‐(2‐phenyl)benzoyl groups, allowing easy access to a variety of spirocyclohexadienes. The addition of water was found to be beneficial in promoting the reaction progress. Investigation of the substrate scope revealed that incorporating an electron‐donating moiety at the 3′‐position of the biphenyl group resulted in a more favorable outcome for spirocycle formation.

A series of novel 2‐(2‐pyridyl)quinazoline luminophores containing a donor aryl fragment at position 4 and methyl or methoxy groups at benzene ring has been synthesized by efficient three‐step route. The linear optical properties have been studied by UV/Vis absorption and photoluminescence spectra in two solvents. We revealed that introduction of additional methyl group or the replacement of methyl substituents with methoxy ones lead to sequentially shift of absorption and emission maximum to blue region. 9H‐Carbazol‐9‐yl‐containing derivative is characterized by hypsochromically shifted absorption band compared to its NEt₂ and NPh₂ counterparts. Unlike 9H‐carbazol‐9‐yl‐derivative, Et₂N‐ and Ph₂N‐bearing quinazolines demonstrate considerable decrease in quantum yield values when going from toluene to MeCN. Solvatochromic properties have been explored, the pronounced bathochromic shift was observed in fluorescence spectra with the increase of solvents polarity. Moreover, the compounds show significant shift of emission band with the increase of water fraction in DMSO/H₂O mixture. Two‐photon optical properties have been also studied, the two‐photon absorption cross‐sections in MeCN and toluene reached 120 GM and 210 GM, respectively. The presence of additional methyl group has little impact on δ_TPA value, while introduction of methoxy substituents dramatically decreases TPA cross sections. Additionally, a quantum‐chemical calculations of synthesized compounds were performed to support the experimental data.

Selective capture of carbon dioxide as a C1 feedstock for the preparation of high‐value chemicals has been recognised as an important way to mitigate the crisis. In this work, a new heterogeneous catalyst, Cu@CP‐PII, was developed through the rational construction of an open‐pore organic skeleton, which is easy to synthesise and highly efficient. With the synergistic effect between the high CO₂ affinity of the porous skeleton and the highly dispersed Cu(I) sites of the activated alkynes, it can be used for the efficient preparation of α‐methylene cyclic carbonates at ambient temperature and pressure. The structure and morphology were exhaustively characterised by Solid State ¹³C‐NMR, FT‐IR, XPS, TEM and N₂ adsorption‐desorption tests, and this catalyst possessed a high surface area of 273.7 m² ⋅ g⁻¹ and uniformly dispersion of CuI. To test its catalytic activity, Cu@CP‐PII in an amount of only 0.4 mol% was used as a catalyst for the carboxylative cyclization reaction of propargylic alcohols with CO₂, which resulted in substrate conversions up to 100 % and yields greater than 99 %. In addition, controlled experiments and mechanistic elucidation confirmed that anhydrous and low temperatures are necessary to achieve high selective control of the target product α‐methylene cyclic carbonates.

Denitrogenative organic transformations and related reactions are a class of significant approaches for carrying out unusual C−C/C‐heteroatom (C−O, C−N, C−S) bond‐forming reactions that are usually promoted by Ru, Ir, Pd, Ni, and Cu metal catalysts. In this trait, numerous methods were adopted to synthesize several pharmaceutically valuable N‐ and O‐containing heteroaromatics using 1,2,3‐benzotriazin‐4(3H)‐one as an electrophilic coupling partner. This review involves the recent achievements related to the metal/organo‐catalyzed thermal and visible‐light mediated denitrogenative approaches with 1,2,3‐benzotriazin‐4(3H)‐ones towards the synthesis of imperative N‐heteroaromatic compounds. In addition, metal and oxidant‐free ortho‐functionalization of benzotriazinones by using suitable nucleophilic partners have been discussed. In particular, the most novel methods employing Ni and Pd metal catalysts that have emerged are exhibited. Specific attention has been paid to offering the detailed mechanistic pathway to explain the role of metal catalysts and the mechanism in the absence of metal catalysts in the denitrogenative reactions under a thermal/visible light medium.

We present herein Brønsted acid‐catalyzed Friedel‐Crafts alkylation of phenols with Donor–Acceptor cyclopropane ketones. The presence of the 1,4‐diphenyl butan‐1‐one and 1,3‐diphenyl propane‐1‐one motifs in various naturally occurring biologically significant molecules inspired us to pursue the direct synthesis of these structural frameworks. Utilizing methanesulfonic acid (MeSO₃H) as a catalyst, we achieved a more environmentally friendly and high‐yielding synthesis, owing to its cost‐effectiveness, biodegradability, transition–metal and additives free conditions. Furthermore, we have successfully extended our developed methodology to thiophenols, resulting in the production of sulfur–based butan‐1‐one derivatives in good yields.

A pressure gauge was incorporated into a two‐chamber glass H‐tube to continuously monitor the pressure inside a reactor when working with gases. The ex situ generated H₂, D₂, acetylene and CO₂ were tested in pressure gauge reactors, and calibration curves were plotted. A series of unsaturated compounds with two or more double C=C bonds accessible for hydrogenation were synthesized for hydrogenation. The hydrogenation proceeded well due to constant pressure control, and the desired products were isolated in good yields. The same hydrogenation procedures were then carried out using steel autoclaves to verify the results and compare them. Surprisingly, almost the same results were obtained, confirming the effectiveness of self‐made glass reactors. The hydrogenation mechanism was further investigated using D‐labeled reagents. The kinetics of hydrogenation was studied both in manometric glass reactors and in steel autoclaves, which showed a similar nature of the main process in both reaction units. Thus, the created reactors can be effectively used in barometric transformations instead of steel autoclaves in appropriate cases.

A metal‐free three‐component reaction for the direct synthesis of α‐sulfonamide phosphonates involving sulfonamide derivatives, benzaldehyde derivatives, and diethyl phosphite, has been achieved with high yields using ethanol as a green solvent. This efficient method reduces reaction time and minimizes the use of excess reagents. Hitherto, no reports have been found in the literature for the direct synthesis of α‐sulfonamide phosphonates from the readily available aldehydes, diethyl phosphite, and sulfonamides, emphasizing the novelty and significance of this work.

Aza[6]helicene and aza[7]helicene were synthesized by Fridel‐Crafts‐type cyclization of axially chiral compounds. From the axially chiral compounds prepared by Fischer indole synthesis, aza[6]helicene and aza[7]helicene were synthesized. Aza[7]helicene was also synthesized from an axially chiral pyrrole compound prepared by Piloty‐Robinson‐type pyrrole synthesis through simultaneous cyclization on both sides of the pyrrole ring. Aza[6]helicene isomerized readily at room temperature, while aza[7]helicene isomerization at room temperature was less likely to proceed. The cell growth inhibitory activity of each enantiomer of N‐Me‐aza[7]helicene in HeLa cells was examined. Differences in the strength of activity between the enantiomers were observed.

The direct ortho‐alkynylation of substituted phenylalanine has been successfully achieved through methoxyiminoacyl (MIA)‐mediated Pd‐catalyzed C−H functionalization. This innovative protocol showcases the ability to apply a diverse range of phenylalanine substrates, resulting in the efficient synthesis of alkynylation benzylamine derivatives with notable effectiveness. Computational investigations further revealed that the fluoride ion enhances the electropositivity of Pd(IV) and the interaction between C1 and C2 within the transition state of the reductive elimination, which significantly expedites the reductive elimination step in the alkynylation process.

The excellent reactivity of diaryliodonium salts has primarily been attributed to the efficient departure of the iodoarene unit, facilitating a variety of arylation reactions. However, one equivalent of iodoarene as a side‐product is a chemical waste in these reactions, which was criticized by chemists for hindering its popularity. Recently, the development of synthetic methodology that preserve the aryl iodine moiety received increasing attention. Oxidative rearrangement reactions involving aryliodonium reagents have significantly addressed the atom‐economic issue, thereby broadening the reaction scope. The resulting intricate aryliodine products are viewed as valuable synthons for the synthesis of natural products, pharmaceutical intermediates and other fine chemicals.