Synthesis of Dithienylcycloalkene Molecular Switches Enabled by a Bench‐Stable Ti‐Complex

Herein, we report a set of cycloalkene‐bridged dithienylethene (DTE) molecular switches with ring sizes ranging from 4‐ to 7‐membered rings. These analogs were accessed via McMurry carbonyl coupling using a bench‐stable Ti(IV)‐complex reagent instead of the generally applied fuming, liquid TiCl 4 , making the synthesis more practical and reproducible. The efficiency of the reaction was dependent on the ring size, providing the lowest yield for the largest, 7‐membered ring. Structures having 3‐membered cyclopropene bridges were prepared using an alternative strategy. Remarkably, the comparison of the photoswitching properties of the series showed that molecules bearing a strained cyclobutene bridge outperform the other switches in terms of reversibility and fatigue resistance.