(+/-)-trans-6,7-Dimethoxy-1-oxo-3-(2-thienyl)isochroman-4-carboxylic acid

Abstract

The title compound, C(16)H(14)O(6)S, was synthesized by the reaction of 6,7-dimethoxyhomophthalic anhydride with thiophene-2-carbaldehyde in the presence of 4-(dimethylamino) pyridine (DMAP) as a basic catalyst. The thiophene ring of the title molecule is disordered over two sites with occupancies of 0.877 (3) and 0.123 (3). The disorder corresponds to an approximate 180 degrees rotation of the thiophene ring with respect to the C-C bond linking it to the rest of the molecule. The six-membered ring of the 3,4-dihydroisochromanone ring system is not planar [puckering parameters Q(T) = 0.571 (2) angstrom, theta = 115.2 (2)degrees and phi = 99.1 (2)degrees]. The benzene ring of the 3,4-dihydroisochromanone ring system makes dihedral angles of 75.0 (2) and 77.2 (5)degrees with the disordered thiophene rings. Intermolecular O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds, as well as C-H center dot center dot center dot pi interactions, lead to the observed supramolecular structure.