The bicyclo[3.1.0] system preferentially adopts a boat-shaped conformation, providing an interesting core for the design of both topological and spatial diversity, thus yielding many possibilities for the embedding of 1,3-disubstituted propylene units in various fixed conformations. This is shown for derivatives with embedded GABA subunits in either trans-trans or trans-gauche conformations, as documented by crystal structures of newly synthesized compounds.
![Two distinct conformations of GABA locked by embedding in the bicyclo[3.1.0]hexane core structure](https://www.iciq.org/wp-content/uploads/2014/03/Two-distinct-conformations_1792.gif)