The ability of liquid crystalline solvent phases to control the stereochemical course of bimolecular thermal reactions of 2,6-dialkoxyanthracenes with a series of fumarates conducted at 130-180 degrees C has been examined, primarily with respect to the structural compatibility of the solutes with the solvent mesogens. For the case of the model thermal [4 + 2] cycloadditions of 2,6-bis(decyloxy)anthracene to bis (trans-4-cyclohexylcyclohexyl) and cholesteryl trans-4-cyclohexylcyclohexyl fumarates at 130-150 degrees C, cholesteryl 2,4-dichlorobenzoate(CDCB) and bis(4-pentyloxyphenyl) trans-1,4-cyclohexanedicarboxylate(BPCD) serve well as cholesteric and smectic liquid crystalline solvents and result in the preferential formation of syn-isomers with an extremely high level of regioselection (syn/anti greater than or equal to 201/1). In contrast, the isotropic solvents with closely related structures give isomer ratios of only greater than or equal to 3/1. Structural similarities between the solutes and the solvent mesogens appear to play a key and influential role in controlling the stereochemical course of the reaction. The temperature dependence for the isomer distribution affords an estimate of the differences of solvation enthalpy and entropy between syn and anti transition states in the anisotropic media.