A new silica-supported organocatalyst based on L-proline: An efficient heterogeneous catalyst for one-pot synthesis of spiroindolones in water

Spiro[4H‐pyran‐3,3′‐oxindoles] Derived from 1,2,3,4‐tetrahydroquinoline—Part 2

“…The first report of the reaction of an isatin with a cyclohexane‐1,3‐dione generating a spiro[4 H ‐pyran‐3,3′‐oxindole], dates back to 1929 . Since then, the multistep process has been re‐examined several times , and in one instance , acyclic 1,3‐diketones were employed successfully. An attempt to use barbituric acid instead of a carbocyclic 1,3‐dicarbonyl compound failed to produce a spiro‐product .…”

Ag/SiO2 as a recyclable catalyst for the facile green synthesis of 3-methyl-4-(phenyl)methylene-isoxazole-5(4H)-ones

“…Performing the reaction with [ 30 mg of catalyst had no significant improvement on the yield or reaction time. However, the decrease in the amount of the catalyst used to 20 and 10 mg affected the product yield by reducing it to 70 and 63 %, respectively (Table 1, entries [19][20][21][22][23]. Therefore, 30 mg of Ag/SiO 2 at RT with water as solvent is assumed as the optimal condition for the model reaction, giving a conversion of 93 % in 1 h.…”

“…The crystalline structure of SiO 2 has been documented as one of the key factors for the justification of the structure-activity relationships of metal-based catalysts [15]. In organic synthesis, silica as support for various metal oxide catalysts allows the design of a varied distribution of its Lewis and Brønsted acidic and basic sites [16][17][18][19] on the surface, facilitating its use as catalyst for specific applications.…”

l-Cysteine-functionalized magnetic nanoparticles (LCMNP): as a magnetic reusable organocatalyst for one-pot synthesis of 9-(1H-indol-3-yl) xanthen-4-(9H)-ones

“…We also investigated the catalytic activity of our previously reported heterogeneous organocatalyst system in this reaction, and it was observed that LCMNP catalyst is more effective than LPMNP [68] and SSLP [69] [71]) were used as in this reaction; however, <50 % of product was (Table 1, entries 18 and 19). These results show that LCMNP catalyst is better in viewpoint of reactivity and experimental conditions for this reaction.…”