Ei elimination: An unprecedented facet of sulfone chemistry

Thermolysis of methyl 3-phenylpropyl sulfone in the gas phase results in fo rmation of allylbenzene. Activation parameters of Delta H-double dagger 53. 5 +/- 1.0 kcal/mol and Delta S-double dagger = -0.7 +/- 1.4 cal/(mol(.)K) w ere obtained over the range of 490-550 degrees C. Similar measurements with a deuterated analogue show a substantial isotope effect, and a lower activ ation enthalpy is observed for the formation of styrene from methyl 2-pheny lethyl sulfone. Along with high-quality ab initio calculations of activatio n parameters and kinetic isotope effects, these results indicate that this is the first reported Ei reaction of a simple sulfone.