Flat versus twisted rotamers of 2,4-disubstituted thiazoles: the effect of intermolecular hydrogen bonds.
In the title compounds, 2-amino-4-(2-chloro-4,5-dimethoxyphenyl)-1,3-thiazole, C(11)H(11)ClN(2)O(2)S, (I), and 4-(2-chloro-4,5-dimethoxyphenyl)-2-methyl-1,3-thiazole, C(12)H(12)ClNO(2)S, (II), the dihedral angles between the thiazole moiety and the chloroaryl group are 51.61 (10) and 8.44 (14), respectively. This difference is a consequence of intermolecular hydrogen bonds forcing the stabilization of a twisted rotamer in (I). Substitution of the amino function by a methyl group precludes these contacts, giving a flat rotamer in (II).
Bernès
Sylvain
S
Centro de Química, Instituto de Ciencias, Universidad Autónoma de Puebla, AP 1613, 72000 Puebla Pue., Mexico. sylvain@eros.pquim.unam.mx
Berros
Martha I
MI
Rodríguez de Barbarín
Cecilia
C
Sánchez-Viesca
Francisco
F