Organocatalytic, rapid and facile cyclotrimerization of isocyanates using tetrabutylammonium phthalimide-N-oxyl and tetraethylammonium 2-(carbamoyl)benzoate under solvent-free conditions

Triaryl‐1,3,5‐triazinane‐2,4,6‐triones (Isocyanurates) Peripherally Functionalized by Donor Groups: Synthesis and Study of Their Linear and Nonlinear Optical Properties

“…Commercial reagents (isocyanates) were used as received. Apart from 1‐H , some 1‐X cyclotrimers have been previously reported ( 1‐NO 2 15b,d, 18 1‐Br ,15b 1‐Me ,15a, 18b 1‐OMe ,2e, 15a,b and 1‐NMe 2 )15b (see the Supporting Information for more details).…”

Green and Facile Synthesis of 4H-Pyran Scaffold Catalyzed by Pure Nano-Ordered Periodic Mesoporous Organosilica with Isocyanurate Framework (PMO-ICS)

“…A proposed mechanistic pathway for the one‐pot three‐component reaction of aldehydes, different 1,3‐dicarbonyl compounds and malononitrile catalyzed by PMO‐ICS ( 1 ) is outlined in Scheme . According to the proposed mechanism, it can be suggested that the enormous hydroxyl groups on the surface of PMO‐ICS ( 1 ) are responsible for the primary activation of both carbonyl group of aldehydes 2 and malononitrile ( 4 ) by hydrogen bonding to facilitate nucleophilic addition of corresponding imine‐ketene resonance form of malononitrile ( 4′ ) on the activated aldehydes ( I ) and formation of intermediate ( II ) ,. The hygroscopic property of the inorganic silica moiety can promote the next step and formation of cyanocinnamonitrile intermediate ( III ) ,,.…”

“…Heteroannulation of this intermediate and its final tautomerization in the presence of PMO‐ICS ( 1 ), as a heterogeneous nanocatalyst, affords the desired products 5 , 6 , or 8 , respectively. Indeed, effective catalytic activity of PMO‐ICS ( 1 ) compared to many silica‐based heterogeneous catalysts containing active Bronsted or Lewis acid centers as well as organocatalysts containing hydroxyl groups can be attributed to appropriate balance between high hydrogen bonding capacity and size‐exclusion (sieve) effect of inorganic silica in one hand and the reduced polarity of the nanocatalyst 1 arising from organic 1,3,5‐tripropyl isocuanurate functionality on the other hand. Therefore, it can be concluded that PMO‐ICS ( 1 ) acts a bifunctional nanocatalyst.…”

“…In continuation of our interest to develop mild, effective and eco‐friendly bifunctional heterogeneous, or homogeneous catalysts for different organic transformations as well as MCRs, we wish herein to report the catalytic activity of pure isocyanurate bridging groups periodic mesoporous organosilica (PMO‐ICS, 1 ), as a green, novel, reusable, and highly effective heterogeneous nanocatalyst for the one‐pot three‐component synthesis of 4 H ‐pyran derivatives in EtOH under reflux conditions (Scheme ).…”

Melamine‐Functionalized Chitosan: A New Bio‐Based Reusable Bifunctional Organocatalyst for the Synthesis of Cyanocinnamonitrile Intermediates and Densely Functionalized Nicotinonitrile Derivatives

“…The useful strategy for the synthesis of medicinal potent functionalized 2‐amino‐6‐(2‐oxo‐2 H ‐chromen‐3‐yl)‐4‐arylnicotinonitrile derivatives is based on the catalytic Knoevenagel condensation between malononitrile/ethyl cyanoacetate and diverse aldehydes following by aryl ketones and ammonium acetate . In continuation of our interest to develop mild efficient organocatalysts for different organic reactions, herein, we report a novel heterogeneous organocatalyst and bio‐based covalently‐modified chitosan using 1,3‐dibromopropane and melamine (Cs−Pr−Me, 1 ) for the Knoevenagel condensation of aldehydes with malononitrile/ethyl cyanoacetate to form cyanocinnamonitrile intermediates. The obtained intermediates can further condensate with aromatic methyl ketones and ammonium acetate to afford functionalized 2‐amino‐6‐(2‐oxo‐2 H ‐chromen‐3‐yl)‐4‐arylnicotinonitrile derivatives (Scheme ).…”