Crystal structures of ten enantiopure Schiff bases bearing a naphthyl group

Abstract

Using a general solvent-free procedure for the synthesis of chiral Schiff bases, the following compounds were synthesized and their crystal structures determined: (S)-(+)-2-{[(1-phenylethyl)imino]methyl}naphthalene, C19H17N, (1), (S)-(+)-2-({[(4-methylphenyl)ethyl]imino}methyl)naphthalene, C20H19N, (2), (R)-(−)-2-({[(4-methoxylphenyl)ethyl]imino}methyl)naphthalene, C20H19NO, (3), (R)-(−)-2-({[(4-fluorophenyl)ethyl]imino}methyl)naphthalene, C19H16FN, (4), (S)-(+)-2-({[(4-chlorophenyl)ethyl]imino}methyl)naphthalene, C19H16ClN, (5), (S)-(+)-2-({[(4-bromophenyl)ethyl]imino}methyl)naphthalene, C19H16BrN, (6), (S)-(+)-2-({[1-(naphthalen-1-yl)ethyl]imino}methyl)naphthalene, C23H19N, (7), (S)-(+)-2-{[(1-cyclohexylethyl)imino]methyl}naphthalene, C19H23N, (8), (S)-(−)-2-{[(1,2,3,4-tetrahydronaphthalen-1-yl)imino]methyl}naphthalene, C21H19N, (9), and (+)-2-({[(1S,2S,3S,5R)-2,6,6-trimethylbicyclo[3.1.1]hept-3-yl]imino}methyl}naphthalene, C21H25N, (10). The moiety provided by the amine generates conformational flexibility for these imines. In the crystals, no strong intermolecular contacts are observed, in spite of the presence of aromatic groups.

Keywords

• crystal structure
• Schiff base
• imine
• naphthyl
• chiral compounds