A standard solution was prepared by dissolving 1,3,5-trimethoxybenzene (10 -20 mg) in 0.5 mL anhydrous CDCl3. Then, 0.1 mL of a standard solution was added to a 3 mm NMR tube. Then, 0.3 mL anhydrous CDCl3 was added, followed by a 0.2 mL aliquot of the [1.1.1]propellane solution. During data collection the d1 relaxation delay was set to 10 s, with 8 scans and 0 dummy scans.