Intriguingly, we discovered a non-typical photolytic reaction unique to Si-Carb 3. Time-dependent photolytic analysis using HPLC-MS tracked a decrease in the mass signal of Si-Carb 3, accompanied by the emergence of a new mass signal corresponding to photolytic products (Figure , Supplementary Figure ). The predominant new signal originated from a photolytic product differ from the typical alcohol-type photolytic product. Structural identification through NMR spectroscopy and mass spectrometry confirmed that this non-typical photolytic conversion of Si-Carb 3 resulted in the formation of vinyl coumarin 6 (Figure ). We hypothesize that the formation of vinyl coumarin 6 involves desilylation during or after photolysis, potentially, proceeding via hydrolysis, intramolecular silylcarbonylation or Peterson-type desilylation. Plausible mechanisms for these reactions are depicted in Supplementary Figure .