For synthetic simplicity, most stilbene substrates were synthesised from naphthyl phosphonium salt S5a, affording [4]or [5]helicenes, depending on whether monocyclic or bicyclic heteroaromatic aldehydes were used as coupling partners. While easy to synthesise, such short helicenes quickly enantiomerise at room temperature in the absence of large substituents along their inner helix. Larger helicenes can avoid this process: the enantiomerisation half-life of [6]helicene is eight orders of magnitude higher than that of [5]helicene. Thus, in the absence of large substituents, helicenes that are to be used as single enantiomers in chiral materials applications should contain at least six rings in their helical backbone to allow their chiral resolution and storage.