Crystal structure, Hirshfeld surface analysis and energy framework study of 6-formyl-7,8,9,11-tetra-hydro-5-pyrido[2,1-]quinazolin-11-one.

At 100 K, the title compound, CHNO, crystallizes in the ortho-rhom-bic space group 2 with two very similar mol-ecules in the asymmetric unit. An intra-molecular N-H⋯O hydrogen bond leads to an (6) graph-set motif in each of the mol-ecules. Inter-molecular π-π stacking and C=O⋯π inter-actions involving the aldehyde O atoms link mol-ecules into stacks parallel to [100].

Stereochemistry of the methyl-idene-bridged quinazoline-iso-quinoline alkaloid 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-]quinazolin-9-one methanol monosolvate.

Two potentially bioactive fragments, namely a tricyclic quinazoline derivative with an exocyclic alkene moiety and a substituted iso-quinoline, are coupled to give 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-]quinazolin-9-one. The target product crystallizes as a methanol solvate, CHNO·CHO, and is configured. The alternative isomer would necessarily imply either considerable twist about the central double bond or very unfavourable intra-molecular contacts between sterically more demanding substituents.

()-6-(Furan-2-yl-methyl-idene)-6,7,8,9-tetra-hydro-pyrido[2,1-]quinazoline-11-thione.

A quinazolinthione, CHNOS, was synthesized by the condensation reaction of 6,7,8,9-tetra-hydro-11-pyrido[2,1-]quinazolin-11-thione with furfural. The mol-ecule crystallizes in the monoclinic system ( space group) and has an configuration with respect to the exocyclic C=C bond. In the crystal, mol-ecules are linked through C-H⋯π(furan) inter-actions, forming zigzag chains propagating along the [001] direction.

Synthesis, tautomeric states and crystal structure of (Z)-ethyl 2-cyano-2-(3H-quinazoline-4-ylidene) acetate and (Z)-ethyl 2-cyano-2-(2-methyl-3H-quinazoline-4-ylidene) acetate.

The new compounds (Z)-ethyl 2-cyano-2-(3H- and 2-methyl-3H-quinazoline-4-ylidene) acetate (1 and 2, respectively) were synthesized by multi-step reactions. The structures in a solution have been determined by (1)H-NMR spectroscopy and in the crystal form by X-ray analysis. Molecule 1 crystallized in a primitive monoclinic cell, space group capital ER, P2(1/c).