Sodium citrate as a highly efficient catalyst is developed for the synthesis of functionalized 2-amino-3-cyano-4H-pyrans and pyran-annulated heterocycles. This method involves one-pot three-component reaction aromatic aldehydes, malononitrile 1,3-dicarbonyl compounds with EtOH: H2O (1:1 v/v) solvent under room temperature. protocol presents several advantages such shorter time, utilization eco-...

Photochromic pyrans for applications in material and life sciences were synthesized via palladium-mediated cyanation, carbonylation and Sonogashira cross-coupling starting from bromo-substituted naphthopyran 1 and benzopyrans 2a/b. A novel photoswitchable benzopyran-based omega-amino acid 6 for Fmoc-based solid-phase peptide synthesis is presented. The photochromic behaviour of the 3-cyano-subs...

The reaction of cyclopentanone with cyanoacetylhydrazine gave 2-cyano-2-cyclopentylideneacetohydrazide (1). Treatment of compound 1 with elemental sulphur in the presence of triethylamine afforded 2-amino-5,6-dihydro- -4H-cyclopenta[b]thiophene-3-carbohydrazide (2), which in-turn formed the corresponding intermediate diazonium salt. The latter was coupled with either ethyl cyanoacetate or ethyl...

Depending on the substitution pattern and the solvent, the gold-catalyzed cyclization of alk-4-yn-1-ones affords different oxygen heterocycles under mild reaction conditions. Alkynones with one substituent at C-3 undergo a 5-exo-dig cycloisomerization to substituted furans , whereas a 6-endo-dig cyclization to 4H-pyrans is observed with substrates bearing two substituents at C-3. In alcoholic s...

A new, simple thermally efficient and solvent-free condensation of 2-amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives with coumarin-3-carboxylic acid employing pentafluorophenylammonium triflate (PFPAT) as an inexpensive organocatalyst for the synthesis of a series of ethyl 4,5-dihydro 7-methyl-2-(2-oxo-2H-chromen-3-yl)-4-oxo-5-aryl-3H-chromeno[2,3-d]pyrimidine-6-carboxyl...

nanoporous sodium montmorillonite clay (na+-mmt) was used as a support for the immobilization of 1-methyl-3-(trimethoxysilylpropyl)-imidazolium hydrogen sulfate (na+-mmt-[pmim]hso4). this catalyst showed excellent catalytic activity for the preparation of 2-amino-3-cyano-5-oxo-5,6,7,8-tetrahydro-4h-benzopyrans via three-component reactions between aldehydes, dimedone and malononitrile. the proc...

In the title compound, C(13)H(18)N(2)O(3), the two H atoms of the NH(2) group are engaged in hydrogen bonding with the N atom of the cyano group and with one O atom of the ethoxy-carbonyl group, building a chain parallel to the [100] direction. The N-H⋯N hydrogen bonds assemble the mol-ecules around inversion centres, forming dimers with an R(2) (2)(12) graph-set motif.

In the title compound, C(23)H(22)N(2)O(3), the pyran ring adopts a twisted boat conformation. The tolyl rings and carboxyl-ate group are attached to the pyran ring with torsion angles of -77.1 (2), 59.5 (3) and 17.8 (3)°, respectively. The ethyl group is disordered over two orientations with a site-occupancy ratio of 0.508 (5):0.492 (5). In the crystal, mol-ecules are linked by N-H⋯N and N-H⋯O ...

The pyran ring of the title compound, C(13)H(18)N(2)O(3), is almost planar (r.m.s. deviation = 0.059 Å). The crystal packing is stabilized by N-H⋯O and N-H⋯N hydrogen bonds.