Synthesis of 2,2,4-trimethyl-1,2- H -dihydroquinoline (TMQ) over selected organosulfonic acid silica catalysts: Selectivity aspects

New Hydrogen-Bond-Enriched 1,3,5-Tris(2-hydroxyethyl) Isocyanurate Covalently Functionalized MCM-41: An Efficient and Recoverable Hybrid Catalyst for Convenient Synthesis of Acridinedione Derivatives

“…Organocatalysis has been emerged as an environmental and cost-effective alternative pathway to the traditional transition-metal catalysis for fine chemical synthesis especially in pharmaceutical industry over recent decades. − Perfect homogeneous organocatalyst must be available through easy synthetic procedures and are often composed of nontoxic small organic compounds that can be easily degraded in the environment without significant waste generation. ,− However, the usual workup remains a major drawback with tedious and costly procedures for separation of the homogeneous organocatalysts from the reaction mixture. On the other hand, heterogeneously catalyzed procedures have a valuable role in simplification of the processes and decreasing environmental concerns, including less corrosion, simple separation, catalysts recovery, and avoiding the usage of hazardous solvents. − To achieve more sustainable catalytic progresses by improving the yield and energy efficiency, recent contributions have also been focused on immobilized organocatalysts onto the surface of solid polymeric supports, in particular silica. − The structure of the obtained organosilica materials is sufficiently attractive and tunable to combine the advantages of a silica matrix, including high surface area, thermal or mechanical stability, as well as chemical inertness with the properties of the grafted organic moieties. ,− Hence, mesoporous silica-based materials (MCM) with very large specific surface areas (up to 2000 m 2 g –1 ) and tunable pore radius from approximately 2–50 nm as well as mechanically stable structure have become a new possible candidate for sensors, adsorbents, − drug-delivery systems, ,, and CO 2 capture or transformation, , as well as solid supports to immobilize homogeneous catalysts − or directly use them as an ideal heterogeneous catalyst alone. − …”

Synthesis and PASS-Assisted Evaluation of New Heterocyclic Compounds Containing Hydroquinoline Scaffold

“…2.1.4. Cyclizations of 7-hydroxy-1,2,2,4-tetramethyl-1,2-dihydroquinoline 3h and 7-hydroxy-1,2,2,4tetramethyl-1,2-dihydroquinoline-6-carbaldehyde, 5e with Methylene Active Compounds 16,17,19,21,22 Dimethylacetylenedicarboxylate (DMAD) is an electron-deficient acetylenic compound which is widely used in cyclization reactions. With phenol, DMAD usually gives adducts, which are the result of addition of the hydroxyl group under both basic and acid catalysis.…”

“…Alkyl derivatives of 1,2-H-dihydroquinoline belong to a large group of quinoline derivatives of great practical importance [16][17][18]. 2,2,4-trimethyl-1,2-H-dihydroquinoline is one of the most important representative, which is considered as a essential and effective anti-oxidant in rubber technologies [19]. The methods of the synthesis of 1,2-quinoline derivatives are based on the cyclization reaction, well known as Skraup reaction and various Skraup-based modification reactions such as Combes, Knorr, Doebner and Friedlander [12,17,[19][20][21].…”

“…2,2,4-trimethyl-1,2-H-dihydroquinoline is one of the most important representative, which is considered as a essential and effective anti-oxidant in rubber technologies [19]. The methods of the synthesis of 1,2-quinoline derivatives are based on the cyclization reaction, well known as Skraup reaction and various Skraup-based modification reactions such as Combes, Knorr, Doebner and Friedlander [12,17,[19][20][21]. Tetrahydroquinoline is one of the most important simple nitrogen heterocycles, being widespread in nature and present in a broad variety of pharmacologically active compounds [22,23].…”

Sulfonated Pyromellitic Dianhydride-functionalized MCM-41: A Multifunctional Hybrid Catalyst for Melting-assisted Solvent-free Synthesis of Bioactive 3,4-dihydropyrimidin-2-(1H)-ones

“…MCM-41 became the most attractive member of the M41S family due to with ordered structure and its special properties such as exceptionally high surface area (> 1000 m 2 g − 1 ), narrow pore-size distribution (1.5-10 nm), and having a hexagonal arrays of cylindrical mesopores [1][2][3][4] . These properties have made MCM-41 known as a support for of metal oxides 5 , heteropoly acids 6 , complexes 7 , drug delivery systems [8][9][10][11][12] , candidate for sensors 13 , degradation inhibitor in polymer dielectrics 14 , adsorption of organic pollutants 15 , and solid supports to immobilize catalysts [16][17][18][19] . However, the acid strength of the pure MCM-41 is relatively weak, which hinders its catalysis applications.…”