Upon photoexcitation, an electron from the nitrogen lone pair of the DABCO is promoted to the redox active ester's valent π orbital. The resultant radical cation and anion pair generated can then fragment into a DABCO cationic radical, phthalimide anion, CO2 and the methyl cyclohexyl radical (R•). This fragmentation is slightly endergonic, with an overall Gibbs formation energy of +3.9 kcal mol -1 . While rapid backward electron transfer (BET)