As the synthesis of polycyclic stilbene coupling partners can involve several steps (c.f. [4]helicene phosphonium salt S5b, SI), we considered other approaches to elongate a helicene and increase the enantiomerisation half-life. Firstly, stilbenes containing bicyclic heteroaromatics can add an extra ring compared to corresponding stilbenes containing monocyclic heteroaromatics. However, a comparison in yields of thieno [6]helicene 2e (53%) and thieno [7]helicene 2p (71%) shows that the extra ring in 2p comes at the cost of a lower yield, likely due to the formation of regioisomers (i.e. 2p', 18% yield, see SI) that cannot form when cyclising directly onto the 5-membered heterocycle. Secondly, double cyclisations such as those affording 2g and 2q can quickly assembly large structures from simple starting materials. While the double stilbene 1g displayed a very low solubility, a similar problem was avoided for 1q by using the solubilising SEM protecting group. Finally, we decided to investigate a modular, stepwise synthesis of longer helicenes. To this end, we performed further functionalisations on the chloro-substituted thienohelicene 2b via Heck or Suzuki reactions, creating longer hetero-stilbene substrates for the Mallory photocyclisation. For the Heck reaction between 2b and styrene, we isolated hetero-stilbene 3a in 51% yield using a procedure developed by Shao and coworkers. For the synthesis of substrate 3b, we selected a Suzuki reaction methodology developed by Zhou and coworkers that afforded the desired product in 80% yield. With our extended length hetero-stilbenes in hand, we subjected substrates 3a and 3b to our Mallory photocyclisation methodology outlined in Table . We were pleased to synthesise thieno [6]helicene 4a and di(thieno) [6]helicene 4b in 80% and 87% yield respectively, some our highest yields thus far for a heterohelicene substrate. Scheme 3: Mallory photocyclization of thieno [4]helicene stilbenes 3a and 3b to afford thieno [6]helicenes 4a and 4b.