Knoevenagel condensation catalyzed by a tertiary-amine functionalized polyacrylonitrile fiber

Efficient tandem synthesis of a variety of pyran-annulated heterocycles, 3,4-disubstituted isoxazol-5(4H)-ones, and α,β-unsaturated nitriles catalyzed by potassium hydrogen phthalate in water

“…The Knoevenagel condensation of aldehydes with active methylene compounds gives rise to the corresponding alkene derivatives. This condensation can be easily conducted in the presence of a variety of catalysts including Lewis acids [140], zeolites [141], amine-functionalized materials [142][143][144], ionic liquids [145,146], and nanomaterials [147,148], each of which gives variable yields of the Knoevenagel adducts. In addition, solid bases [149,150] and organic bases, for example piperidine, pyridine, urea, DABCO, and guanidine [151][152][153], have been used for Knoevenagel condensations.…”

Synthesis of Polyacrylonitrile Fiber‐Supported Poly(ammonium methanesulfonate)s as Active and Recyclable Heterogeneous Brønsted Acid Catalysts

“…[10] Given many advantages such as low cost, high strength, corrosion and mildew resistant as well as potential performance for a fixed-bed reactor of PANF, the development of PANF-supported acid catalysts for heterogeneous catalysis would be of great interest and value. Moreover, the amine methanesulfonates acting as the Brønsted acid catalyst have been verified in the tetrahydropyranylation of alcohols.…”

Synthesis of 5‐Amino‐3,3‐dimethyl‐7‐phenyl‐3H‐[1,2]oxathiolo[4,3‐b]pyridine‐6‐carbonitrile 1,1‐Dioxides

“…As shown in Scheme 2 and as expected, the reaction of 4-amino-5,5-dimethyl-5H-1,2-oxathiole 2,2-dioxide (1) [7] with readily available 2(arylidene)malonitriles, such as commercial benzylidenemalononitrile (2a), 2-(4-methoxybenzylidene)malononitrile (2b) [19], 2-(3,4-dimethoxybenzylidene)malononitrile (2c) [20], 2-(4-methylbenzylidene) malononitrile (2d) [21], and 2-(4-methylbenzylidene)malononitrile (2e) [22], catalyzed by piperidine in ethanol at reflux after 2-4 h, cleanly afforded 5-amino-3,3-dimethyl-7-aryl-3H- [1,2]oxathiolo [4,3-b]pyridine-6-carbonitrile 1,1-dioxides (3) (Scheme 2) in variable yields ranging from 11% (3e) to 43% (3d) (see Experimental). All our efforts directed to improve these chemical yields, by using toluene or ethyl ether as solvent, were fruitless.…”

“…The solvent was removed, and the crude was submitted to purification by column chromatography. [7] (163 mg, 1.0 mmol), 2-(4-methoxybenzylidene)malononitrile (2b) [19] (184 mg, 1.0 mmol), and piperidine (cat.) in ethanol (10 mL) was refluxed for 2 h. The reaction was cooled, water was added, and the solid was recrystallized to give 5-amino-7-(4-methoxyphenyl)-3,3-dimethyl-3H- [1,2] [7] (163 mg, 1.0 mmol), 2-(4-methylbenzylidene) malononitrile (2d) [22] (168 mg, 1.0 mmol), and piperidine (cat.)…”