Dimethyl 1-(4-methylphenyl)-8-(thiophen-2-yl)-11-oxatricyclo[6.2.1.0^2,7]undeca-2,4,6,9-tetraene-9,10-dicarboxylate

Abstract

Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.002 Å; disorder in main residue; R factor = 0.041; wR factor = 0.129; data-to-parameter ratio = 17.0.The title compound, C 25 H 20 O 5 S, is the product of a DielsAlder reaction. The molecule consists of a fused tricyclic system containing two five-membered rings and one sixmembered ring. The five-membered rings both show an envelope conformation with the O atom at the flap, whereas the six-membered ring adopts a boat conformation. The thiophene ring is disordered over two sets of sites with an occupancy ratio of 0.53 (1):0.47 (1). The dihedral angles between the 4-methylphenyl ring and the major and minor components of the thiophene ring are 66.3 (1) and 67.9 (1) , respectively, while the dihedral angle between the disordered thiophenyl components is 3.1 (1) . The mean plane of the tricyclic ring system makes dihedral angles of 35.8 (1), 30.8 (1) and 32.8 (1) , respectively, with the 4-methylphenyl ring and the major and minor components of the thiophenyl ring. In the crystal, inversion dimers are formed through pairs of C-HÁ Á Á interactions. In addition, C-HÁ Á ÁO interactions are observed. Related literatureFor background to Diels-Alder reactions, see: Denmark & Thorarensen (1996). For related structures, see: Ohwada et al.