The ratios of stereoisomeric products in the hetero-and homogeneous DielsAlder additions of cyclopentadiene to acrolein in various solvents (diethyl ether
acetone
dichloromethane
ethanol and water) were determined. The endo/exo product ratio of the homogeneous reactions in the solutions increases slightly with increasing solvent polarity; Ia the heterogeneous:Diels-Alder reactions
however
the distribution of the products in different media is not a simple relationship.