Crystal structures of ten enanti­opure Schiff bases bearing a naphthyl group

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, C(19)H(17)N, (1), (S)-(+)-2-({[(4-methyl­phen­yl)eth­yl]imino}­meth­yl)naphthalene, C(20)H(19)N, (2), (R)-(−)-2-({[(4-meth­oxy­lphen­yl)eth­yl]imino}­meth­yl)naphthalene, C(20)H(19)NO, (3), (R)-(−)-2-({[(4-fluoro­phen­yl)eth­yl]imino}­meth­yl)naphthalene, C(19)H(16)FN, (4), (S)-(+)-2-({[(4-chloro­phen­yl)eth­yl]imino}­meth­yl)naphthalene, C(19)H(16)ClN, (5), (S)-(+)-2-({[(4-bromo­phen­yl)eth­yl]imino}­meth­yl)naphthalene, C(19)H(16)BrN, (6), (S)-(+)-2-({[1-(naphthalen-1-yl)eth­yl]imino}­meth­yl)naph­thalene, C(23)H(19)N, (7), (S)-(+)-2-{[(1-cyclo­hexyl­eth­yl)imino]­meth­yl}naph­tha­lene, C(19)H(23)N, (8), (S)-(−)-2-{[(1,2,3,4-tetra­hydro­naphthalen-1-yl)imino]meth­yl}naphthalene, C(21)H(19)N, (9), and (+)-2-({[(1S,2S,3S,5R)-2,6,6-tri­methylbi­cyclo­[3.1.1]hept-3-yl]imino}­meth­yl}naphthalene, C(21)H(25)N, (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.