Fig. 5. Mechanistic studies. (a) UV-vis measurements acquired on a Shimadzu UV-2401PC spectrophotometer with a quartz cuvette with path length of 1 cm. All samples in Et2O. Vial A (green line): [catalyst C] = 0.6 M, [1a] = 0.6 M and [2,6-lutidine] = 0.6 M; vial B (purple line): [2a] = 0.6 M; vial C: [catalyst C] = 0.6 M, [1a] = 0.6 M, [2a] = 0.6 M and [2,6-lutidine] = 0.6 M. While the individual reaction components are all colourless, the vial C mixture containing all reaction components displays a yellow colour and an absorption band from approximately 450 nm. (b) Proposed radical propagation mechanism triggered by the excitation of the dienamine-based EDA complex III, which serves as the initiation event.
