Diversity synthesis of N-substituted 2-amino-1,6-naphthyridine derivatives under microwave irradiation.

A sequential three-component reaction of 3,5-diarylidenepiperidin-4-one, malononitrile, and amine (such as aromatic amine, cyclopropanamine, and NH(4)OAc) in acetic acid under microwave irradiation has been developed. In this one-pot reaction, a series of new N-substituted 2-amino-1,6-naphthyridine derivatives were synthesized with excellent yields. This method has the advantages of operational simplicity and increased safety for small-scale fast synthesis of N-aryl 2-amino-1,6-naphthyridines for biomedical screening.

Diversity synthesis of pyrimido[4,5-b][1,6]naphthyridine and its derivatives under microwave irradiation.

A series of new heterocyclic compounds, involving pyrimido[4,5-b][1,6]-, benzo[b][1,6]-, pyrazolo[3,4-b][1,6]naphthyridine, and aza-benzo[b]fluorene skeletons were successfully synthesized via the reaction of structurally diverse 3,5-dibenzylidenepiperidin-4-one with various enamine-likes (2,6-diaminopyrimidin-4(3H)-one, 3-amino-5,5-dimethylcyclohex-2-enone, 3-methyl-1-phenyl-1H-pyrazol-5-amine and 1H-benzo[d]imidazol-2-amine) in glycol under microwave irradiation. This method has the advantages of short synthetic route, operational simplicity, and increased safety for small-scale fast synthesis for biomedical screening.

Synthesis of isoxazolo[5,4-b]pyridines by microwave-assisted multi-component reactions in water.

A series of new polycyclic-fused isoxazolo[5,4-b]pyridines were obtained by a one-pot tandem reaction under microwave irradiation in water. Without any use of additional reagent or catalyst, the synthetic protocol represents a green one and makes this methodology suitable for library synthesis in drug discovery efforts.

A new mild base-catalyzed Mannich reaction of hetero-arylamines in water: highly efficient stereoselective synthesis of beta-aminoketones under microwave heating.

A new mild base-catalyzed Mannich reaction of aromatic aldehydes with 1,2-diphenylethanone and hetero-arylamines including pyridin-2-amine and pyrimidin-2-amine is described. In this reaction, a series of new beta-aminoketones were stereoselectively synthesized in water by controlling the steric hindrance of the substrates under microwave heating. This method has the advantages of a short synthetic route, operational simplicity, increased safety for small-scale high-speed synthesis, and minimal environmental impact.

Design and microwave-assisted synthesis of naphtho[2,3-f]quinoline derivatives and their luminescent properties.

A sequential three-component reaction of an aromatic aldehyde with an equimolar amount of 2-aminoanthracene and cyclic 1,3-dicarbonyl compounds (such as tetronic acid, 5,5-dimethyl,3-cyclohexanedione, 1,3-indanedione, 3H-chromene-2,4-dione, quinoline-2,4(1H, 3H)-dione and barbituric acid) in acidic medium under microwave irradiation has been developed. In this one-pot reaction, a series of unusual fused heterocyclic compounds, naphtho[2,3-f]quinoline derivatives, were synthesized. This method has the advantages of operational simplicity, increased safety for small-scale fast synthesis, and minimal environmental impact. Most distinctively, this new class of naphtho[2,3-f]quinoline derivatives exhibit good luminescent properties in the ethanol solution, which can be used potentially as organic electroluminescent (EL) media.

An efficient and chemoselective synthesis of benzo[e][1,4]thiazepin-2(1H,3H,5H)-ones via a microwave-assisted multi-component reaction in water.

A new and efficient strategy for the synthesis of benzo[e][1,4]thiazepin-2(1H,3H,5H)-ones via a microwave-assisted multi-component reaction in aqueous media is described.

Microwave-assisted combinatorial synthesis of new 3-pyrimidin-5-ylpropanamides via a solvent-dependent chemoselective reaction.

A series of new 3-pyrimidin-5-ylpropanamides was selectively synthesized via a microwave-assisted, chemoselective reaction of arylidene-Meldrum's acid, 6-hydroxypyrimidin-4(3H)-one, and structurally diverse amines including (S or R)-1-phenylethanamine, cyclohexanamine, and cyclopentanamine depended on nature of solvents. In this reaction, the utilization of HOAc as a solvent leads to 3-pyrimidin-5-ylpropanamides, whereas water as reaction media results in the spiro[5.5]undecane-1,5,9-triones from same starting materials. This method has the advantages of short synthetic route, operational simplicity, increased safety for small-scale high-speed synthesis, and minimal environment impact.

3,6-Dimethyl-1-phenyl-4-(2-thien-yl)-8-(2-thienylmethyl-ene)-5,6,7,8-tetra-hydro-1H-pyrazolo[3,4-b][1,6]naphthyridine.

In the mol-ecule of the title compound, C(26)H(22)N(4)S(2), the pyrazole ring is oriented at a dihedral angle of 0.85 (3)° with respect to the adjacent naphthyridine ring, while the other ring of naphthyridine adopts an envelope conformation. The dihedral angle between phenyl and pyrazole rings is 87.65 (3)°. In the crystal structure, weak inter-molecular C-H⋯N inter-actions link the mol-ecules into chains. The π-π contacts between the naphthyridine rings and the naphthyridine and thio-phene rings [centroid-centroid distances = 3.766 (3) and 3.878 (3) Å] may further stabilize the structure. A weak C-H⋯π inter-action is also present.