Synthesis and Crystal Structures of 2-Amino-4-methyl-5,6,7,8-tetrahydroquinoline-3-carbonitrile and 2-Amino-4-phenyl-4a,5,6,7-tetrahydro-4H-naphthalene-1,3,3-tricarbonitrile

Abstract

2-Amino-4-methyl-5,6,7,8-tetrahydroquinoline-3-carbonitrile with m.f. C₁₁H₁₃N₃ was synthesized using simple multicomponent reaction of cyclohexanone, malononitrile and acetaldehyde. However, in an effort to synthesize another analogue of I using benzaldehyde in placement of acetaldehyde, 2-amino-4-phenyl-4a,5,6,7-tetrahydro-4H-naphthalene-1,3,3-tricarbonitrile (II) [C₁₉H₁₆N₄] was formed. The compounds I and II were crystallized in triclinic and orthorhombic crystal system with space group P-1 and Pbca. The two carbon atoms in tetrahydroquinoline-3-carbonitrile were disordered over two positions which were refined using EADP constraint. The dihedral angle puckering parameters of different planes were measured. It is found that both of these molecules are involved in classical N-H…N type hydrogen bonding interaction which forms dimers through the formation of different ring motifs i.e. R₂² (8) and R₂² (12). In quinoline-3-carbonitrile N-H…N interactions forms sheets along ab plane while in naphthalene-1,3,3-tricarbonitrile infinite two dimensional network stabilize the crystal structure along (0 0 1) plane.