Diastereoselective synthesis of isoxazolidines and spiroisoxazolidines via catalytic 1,3-dipolar cycloaddition reactions in the presence of Fe 3 O 4 - l -proline nanoparticles as a magnetic organocatalyst

On Searching for a Stepwise Channel for the Mechanism of a 1,3-Dipolar Cycloaddition between a Thiocarbonyl S-Oxide and C20 Fullerene using Born–Oppenheimer ab Initio QM/MM Molecular Dynamics

“…Therefore, it was found that in the case of this reaction, there is no stepwise reaction route and the only possible mechanism is the usual concerted pathway. Also, it should be noted that, due to the fact that much research on the stepwise or concerted nature of the mechanism of 1,3-dipolar cycloaddition reactions has been performed by the DFT method, in this project we have used this approach to obtain some useful results [12][13][14][15][16][17][18][19][20]. Table 1 shows that the concerted reaction of the methyl thiocarbonyl S-oxide occurred in a fast process with a rate constant of 9.47 × 10 10 M -1 s -1 due to the ∆G # of the process (2.47 kcal mol -1 ), while the rate constant for the dimethyl derivative is about 4.84 × 10 11 M -1 s -1 , due to the ∆G # of the process (1.51 kcal mol -1 ), showing that the dimethyl derivative has a faster rate.…”

“…Some other researchers (e.g. Jasiński et al [12][13][14], Zahedi et al [15,16] and Siadati [17][18][19][20]) found other stepwise examples especially for non-thiocarbonyl ylides. Firestone published his completed and updated theory insisting on his diradical-stepwise mechanism [21].…”

Nanoparticle‐Catalysed 1,3‐Dipolar Cycloadditions

“…[29] The diastereoselectivity towards the endo isoxazolidine is consistent yield and are the result of the three-component reaction between N-aryl-hydroxylamines, aromatic aldehydes and the appropriate dipolarophile. [30] This latter species should be the iminium intermediate, which arises from the condensation between the L-proline supported on the nanocatalyst and crotonaldehyde. The diastereopreference towards the endo-isoxazolidines as well as the observed ee.…”

“…It is noteworthy that inorganic nanoparticles can be active catalysts for cycloadditions also when coated with chemisorbed organic molecules (Figure a) . In another strategy, the inorganic nanoparticles are decorated with catalytic moieties, e.g., organic catalysts,, metal complexes,, or other nanoparticles (Figure b,c) . The advantages of this strategy are the easy separation of the catalyst from the reaction mixture, especially when magnetic nanoparticles are employed, and a possible improvement of the catalytic activity thanks to multi‐presentation of the active sites .…”

Preparation and characterization of Fe3O4@SiO2/APTPOSS core–shell composite nanomagnetics as a novel family of reusable catalysts and their application in the one‐pot synthesis of 1,3‐thiazolidin‐4‐one derivatives

“…In recent years, utilizing environmental catalysts which can be simply recycled has received significant attention . In the study reported here, in continuation of our recent researches on the synthesis of nanoparticles, we prepared a novel recyclable heterogeneous core–shell nanomagnetic Fe 3 O 4 @SiO 2 /octakis[3‐(3‐aminopropyltriethoxysilane)propyl]octasilsesquioxane, using iron oxide MNPs as the core and the organic–inorganic hybrid silica as the shell. Then, the inorganic–organic hybrid POSS MNPs were used as an efficient new heterogeneous catalyst for the one‐pot three‐component synthesis of 1,3‐thiazolidin‐4‐ones under solvent‐free conditions (Scheme ).…”