Preparation and photochemical reactivity of dimethyl malonate ylides of thioanisole, thiophene, benzothiophene, and dibenzothiophene

ORGN 86

Stacey A. Stoffregen, sstoffre@iastate.edu and William S. Jenks, wsjenks@iastate.edu. Department of Chemistry, Iowa State University, 3815 Gilman Hall, Ames, IA 50011
We have previously shown that dibenzothiophene-S-oxide (DBTO) undergoes deoxygenation upon photolysis. We hope to extend this chemistry to the generation of reactive intermediates such as carbenes and nitrenes through the photochemical scission of the S-C and S-N bonds of sulfonium ylides and sulfilimines. Dimethyl malonate ylides of thioanisole, thiophene, benzothiophene, and dibenzothiophene have been prepared. Chemical trapping studies with cyclohexene and methanol are suggestive of a carbene intermediate. The quantum yields of sulfide formation upon photolysis from the thiophene, benzothiophene, and dibenzothiophene ylides are all greater than that of DBTO. Further product studies and time-resolved IR studies will be used to unambiguously establish the presence and multiplicity of the intermediate carbenes generated.