The torquoselectivity in an electrocyclic reaction refers to the direction that the substituents rotate. For example, the substituents in a reaction that is conrotatory can still rotate in two directions. It produces a mixture of two products that are the mirror image of each other (enantiomeric products). A reaction that is torquoselective restricts one of these directions of rotation (partially or completely) to produce a product in enantiomeric excess (where one stereoisomer is produced much more than the other).