Isoquinoline-catalyzed reaction between 4-hydroxycoumarin or 4-hydroxy-6-methylpyran-1-one and dialkyl acetylene dicarboxylates: synthesis of coumarin and pyranopyrane derivatives

In this work we report the reaction between dialkyl acetylenedicarboxylates and enolic systems such as 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclohexanedione, 4-hydroxycoumarin or 4-hydroxy-6-methylpyran-1-one in the presence of isoquinoline, which leads to new coumarin and pyranopyran derivatives

catena-Poly[[bis­(pyrazine-2-carbox­amide-κN 4)mercury(II)]-di-μ-bromido]

In the crystal structure of the title compound, [HgBr2(C5H5N3O)2]n, the HgII cation is located on an inversion center and is coordinated by two N atoms from the pyrazine rings and four bridging Br− anions in a distorted octa­hedral geometry. The Br− anions bridge the HgII cations with significantly different Hg—Br bond distances of 2.4775 (8) and 3.1122 (8) Å, forming polymeric chains running along the a axis. Inter­molecular N—H⋯O and N—H⋯N hydrogen bonds are effective in the stabilization of the crystal structure

(4,4′-Dimethyl-2,2′-bipyridine-κ2 N,N′)diiodidomercury(II)

In the mol­ecule of the title compound, [HgI2(C12H12N2)], the HgII atom is four-coordinated in a distorted tetra­hedral configuration by two N atoms from the 4,4′-dimethyl-2,2′-bipyridine ligand and by two I atoms. There is a π–π contact between the pyridine rings [centroid–centroid distance = 3.775 (6) Å]

(2Z)-N-(4-Meth­oxy­phen­yl)-2-(4-meth­oxy­phenyl­imino)-2H-1,4-benzoxazin-3-amine

In the crystal structure of the title compound, C22H19N3O3, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules into a zigzag chain parallel to the face diagonal of the ac plane. The meth­oxy phenyl rings make a dihdral angle of 32.38 (7)° and form dihedral angles of 0.66 (8) and 24.17 (7)° with the fused benzooxazine ring system

(Z)-N-[5-Bromo-2-(4-methyl­anilino)-3H-indol-3-yl­idene]-4-methyl­aniline oxide

The crystal structure of the title compound, C22H18BrN3O, is stabilized by π–π contacts [centroid–centroid distance = 3.476 (2) Å] between five-membered rings as well as inter­molecular C—H⋯O and C—H⋯N hydrogen bonds. An intra­molecular N—H⋯O hydrogen bond occurs. The benzene rings make a dihedral angle of 59.89 (8)°. The dihedral angles between the fused ring systemand the two benzene rings are 3.46 (7) and 61.97 (7)°