Nano-titania sulfuric acid-promoted synthesis of tetrahydrobenzo[b]pyran and 1,4-dihydropyrano[2,3-c]pyrazole derivatives under ultrasound irradiation

Ultrasound and Nano‐Catalysts: An Ideal and Sustainable Combination to Carry out Diverse Organic Transformations

“…(Scheme ) successfully employed magnetic nano‐lanthanum strontium magnesium oxide (La 0.7 Sr 0.3 MnO 3 ) as an efficient and recyclable catalyst for the synthesis of 2‐amino‐3‐cyano‐tetrahydro‐4 H ‐benzo[ b ]pyrans ( 37 ) via a one‐pot three‐component condensation between aromatic aldehydes ( 1 ), malononitrile ( 34 ) and dimedone ( 36 ) in ethanol under ultrasonic irradiation at room temperature. The same group has also investigated the catalytic applicability of nano‐titania sulfuric acid on the same batch of the reaction under ultrasonic irradiation in ethanol at 40 °C (Scheme ) . In 2015, Fe 3 O 4 @SiO 2 ‐imid‐H 3 PMo 12 O 40 nanoparticles was used by Esmaeilpour et al .…”

Synthesis of heterocycles and fused heterocycles catalyzed by nanomaterials

“…18) for the synthesis of pyrazines 52a-d from the reaction of the appropriate diamines 51a,b with the corresponding 1,2-diketone 25. 70 As shown in Table 26, the ease of the reaction is directly related to the substituents attached to the benzene ring and the spatial accessibility of aldehyde 7 as well. 66 The same group reported also the synthesis of highly functionalized 4H-chromenes 56 in the presence of nanotitania sulfuric acid (15-nm TSA) as a heterogeneous catalyst.…”

Pd(0)‐guanidine@MCM‐41: a very effective catalyst for rapid production of bis (pyrazolyl)methanes

“…[21,24,25] In this technique, more than two starting materials react together in a one-pot reaction to form a product wherein all or most of the reactants atoms contribute. [26][27][28][29] That is important from the atom economic standpoint. [30] Environmental friendly operation via reducing the number of synthetic steps and work up, the energy consumption, reaction time, waste production, and eliminating the isolation of unstable intermediates are among the advantages of MCRs.…”