Synthesis of ethyl 5-cyano-6-hydroxy-2-methyl-4-(1-naphthyl)-nicotinate

Multicomponent Synthesis of Unsymmetrical Derivatives of 4-Methyl-Substituted 5-Nitropyridines

The multicomponent reaction of 2-nitroacetophenone (or nitroacetone), acetaldehyde diethyl acetal, β-dicarbonyl compound, and ammonium acetate in an acetic acid solution allowed the acquisition of previously undescribed 4-methyl-substituted derivatives of 5-nitro-1,4-dihydropyridine in satisfactory yields. The oxidation of the obtained 5-nitro-1,4-dihydropyridine derivatives resulted in the corresponding 2,4-dimethyl-5-nitropyridines. In addition, for the first time in the synthesis of unsymmetrical 1,4-dihydropyridines by the Hantzsch reaction acetaldehyde, diethyl acetal was used as a source of acetaldehyde. The use of more volatile and sufficiently reactive acetaldehyde in this reaction did not lead to a controlled synthesis of unsymmetrical 5-nitro-1,4-dihydropyridines. The proposed multicomponent approach to the synthesis of 4-methyl-substituted 5-nitro-1,4-dihydropyridines and their subsequent aromatization into pyridines made it possible to obtain previously undescribed and hardly accessible substituted 5(3)-nitropyridines.

Facile Synthesis of Pyridines from Propargyl Amines: Concise Total Synthesis of Suaveoline Alkaloids

A general and efficient protocol was developed for the synthesis of polysubstituted pyridines from propargyl amines and unsaturated carbonyl compounds through a tandem condensation/alkyne isomerization/6π 3-azatriene electrocyclization sequence. This process was found to be applicable to a wide range of readily available substrates (30 examples, up to 95 % yield) and could be readily performed on a preparative (20 g) scale. By taking advantage of this method for late-stage pyridine incorporation, we successfully completed the collective total synthesis of suveoline, norsuveoline, and macrophylline.

Expedient, catalyst-free, three-component synthesis of fused tetrahydropyridines in water

An expedient, three-component synthesis of oxazolo[3,2-a]pyridines and pyrido[2,1-b][1,3]oxazines was achieved under catalyst-free conditions in water.

P2W18O62·24H2O as an efficient and recyclable catalyst for the ecofriendly preparation of β-aminocrotonates

H6P2W18O62·24H2O bulk- and silica-supported catalysts were found to be efficient and recyclable catalysts for the synthesis of a series of β-aminocrotonates using toluene as the solvent or under no solvent reaction conditions. Several substituted β-aminocrotonates can be prepared in very good yields and purity by direct reaction of amines and 1,3-dicarbonyl compounds in the presence of a catalytic amount of bulk- and silica-gel-supported H6P2W18O62·24H2O. The title compounds were prepared in very good yields using both methodologies, and no secondary products were detected. The procedure using no reaction solvent resulted in a clean and useful alternative, which has the advantages of a greener methodology with operative simplicity, the use of a reusable and noncorrosive solid catalyst, soft reaction conditions, low reaction times, and good yields.

4-(2,4-Dichloro-phen-yl)-6-(1H-indol-3-yl)-2,2'-bipyridine-5-carbonitrile

The title compound, C(25)H(14)Cl(2)N(4), crystallizes with two independent mol-ecules in the asymmetric unit. The two pyridine rings are almost coplanar, making dihedral angles of 3.2 (1) and 8.6 (1)° in the two independent mol-ecules. The dichloro-phenyl and indole rings are twisted away from the bipyridine ring by 64.32 (5) and 18.46 (4)°, respectively in the first molecule and by 51.0 (1) and 27.99 (5)°, respectively in the second molecule. The crystal packing is stabilized by C-H⋯N, C-H⋯Cl, N-H⋯N and C-H⋯π inter-actions.