Efficient synthesis of pyrano[2,3-c]coumarins via intramolecular domino Knoevenagel hetero-Diels–Alder reactions

Regioselective synthesis of fused oxa-heterocycles via iodine-mediated annulation of cyclic 1,3-dicarbonyl compounds with propargylic alcohols

The synthesis of structurally diverse fused oxa-heterocycles is established through the iodine-mediated cascade annulation of cyclic 1,3-dicarbonyl compounds with propargylic alcohols.

Two step, one-pot sequential synthesis of functionalized hybrid polyheterocyclic scaffolds via a solid state melt reaction (SSMR)

A new one pot assembly of highly functionalized benzo[a]phenazinone fused chromene/bicyclic scaffolds via a domino Knoevenagel intramolecular hetero-Diels-Alder (IMHDA) strategy using a solid state melt reaction (SSMR) of 2-hydroxynaphthalene 1,4-dione, o-phenylenediamine, O-allyl salicylaldehyde/O-vinyl salicylaldehyde derivatives is reported. The formation of five new bonds (two C-C bonds and three C-O bonds), three six-membered rings, and three stereogenic centers in a one-pot manner is very attractive. Ease of reaction with short time, good yields with water as the only byproduct and work up free procedure are some of the excellent features of the present protocol.

Coumarin heterocyclic derivatives: chemical synthesis and biological activity

This review highlights the broad range of science that has arisen from the synthesis of coumarin-linked and fused heterocycle derivatives. Specific topics include their synthesis and biological activity.

Computational and spectral studies of 6-phenylazo-3-(p-tolyl)-2H-chromen-2-one

6-Phenylazo-3-(p-tolyl)-2H-chromen-2-one 4 was prepared and characterized by IR, (1)H, and (13)C NMR spectral studies. The optimized structure of the chromen-2-one 4 was investigated by the Gaussian 03 B3LYP density functional method calculations at 6-31G(d,p) basis set. The gauge-independent atomic orbital (GIAO) (13)C and (1)H chemical shift calculations for the synthesized chromen-2-one in CDCl3 were also made by the same method. The computed IR frequencies of the chromen-2-one and the corresponding vibrational assignments were analyzed by means of potential energy distribution (PED%) calculation using vibrational energy distribution analysis (VEDA) program. The first order hyperpolarizability (βtot), polarizability (α) and dipole moment (μ) were calculated using 6-311G(d,p) basis set and the nonlinear optical (NLO) properties are also addressed theoretically. Stability of the chromen-2-one 4 molecule has been analyzed by calculating the intramolecular charge transfer using natural bond order (NBO) analysis. The molecular electrostatic potentials, HOMO-LUMO energy gap and geometrical parameters were also computed. Topological properties of the electronic charge density in chromen-2-one 4 were analyzed employing the Bader's Atoms in Molecule (AIM) theory which indicated the presence of intramolecular hydrogen bond in the molecule.

Ohmic heating assisted synthesis of coumarinyl porphyrin derivatives

Efficient access to coumarinyl porphyrin derivatives bearing pyrano[3,2-c]coumarin motifs is disclosed. Conditions used ohmic heating and water, in Knoevenagel and hetero-Diels–Alder reactions between a beta-vinylporphyrin and α-methylenechromanes.

A copper-catalyzed one-pot, three-component tandem conjugative alkynylation/6-endo cyclization sequence: access to pyrano[2,3-d]pyrimidines

A copper-catalyzed one-pot, atom/step-economical, three component method for the construction of pyrano[2,3-d]pyrimidines has been developed via a tandem conjugative alkynylation/6-endo cyclization sequence.

Graphene oxide nanosheets as metal-free catalysts in the three-component reactions based on aryl glyoxals to generate novel pyranocoumarins

Graphene oxide (GO) was employed as an efficient and powerful catalyst in one-pot, three-component synthesis of new pyranocoumarins.

Easy Access to Coumarin Derivatives Using Alumina Sulfuric Acid as an Efficient and Reusable Catalyst under Solvent-Free Conditions

A new and efficient condition for the use of alumina sulfuric acid (ASA) as a heterogeneous catalyst in the Pechmann condensation reaction in solvent-free condition for the formation of coumarins has been reported.

Synthesis of some novel annulated pyrido[2,3-d]pyrimidines via stereoselective intramolecular hetero Diels-Alder reactions of 1-oxa-1,3-butadienes

Some novel annulated pyrido[2,3-d]pyrimidines 6 and 7 were synthesized stereoselectively by intramolecular hetero Diels-Alder reactions involving 1-oxa-1,3-butadienes.