 The development of an enantioselective Nazarov cyclization is a desirable addition to the repertoire of Nazarov cyclization reactions . To that end , several variations have been developed utilizing chiral auxiliaries and chiral catalysts . Diastereoselective cyclizations are also known , in which extant stereocenters direct the cyclization . Almost all of the attempts are based on the idea of torquoselectivity ; selecting one direction for the vinyl groups to " rotate " in turn sets the stereochemistry as shown below . 
