PHOTOCHEMICAL-REACTIONS OF SACCHARIN-ALPHA-SILYLAMINE SYSTEMS - DESILYLMETHYLATION OF ALPHA-SILYLAMINE VIA SINGLE-ELECTRON TRANSFER PATHWAY

Photochemical reactions of saccharin with tertiary amines were explore d. Saccharin was found to undergo an acid-base reaction with N-trimeth ylsilylmethyl-N,N-diethyl amine to farm N-trimethylsilylmethyl-N,N-die thyl ammonium saccharin salt which is in equilibrium with free sacchar in and N-trimethylsilylmethyl-N,N-diethyl amine in solution. Photoreac tion of N-trimethylsilylmethyl-N,N-diethyl ammonium saccharin in CH3OH or CH3CN results in the generation of desilylmethylated product, N,N- diethyl ammonium saccharin mainly along with benzamide. Photoreaction of N-methylsaccharin with N-trimethylsilylmethyl-N,N-diethyl amine in CH3OH leads to the production of o-(N-methylcarbamoyl)-N-ethylbenzenes ulfonamide as the major product along with N-methylbenzamide as the mi nor product. On the other hand, photoreaction of N,N,N-triethyl ammoni um saccharin, generated from saccharin and triethylamine, produces N-m ethylbenzamide as the exclusive product. These photoreactions are quen ched by oxygen indicating that triplets of saccharin and N-methylsacch arin are the reactive excited states. Based on the consideration of th e redox potentials of saccharin and N-trimethylsilylmethyl-N,N-diethyl amine, and the nature of photoproducts, pathways involving initial tr iplet state single electron transfer are proposed for photoreactions o f the saccharins with the alpha-silylamine.