REACTION OF SODIUM METHOXIDE WITH ALPHA-BROMOBENZYL SULFONE AND WITH 2,3-DIPHENYLTHIIRENE 1,1-DIOXIDE

Kinetic and product determination studies have shown that (PhCHBr)2SO2 (I) reacts with methoxide ion in methanol to give 2-bromo-2,3-diphenylthiirane 1,1-dioxide (3, not isolated), which is rapidly converted into 2,3-diphenylthiirene 1,1-dioxide (4). The latter cannot be isolated under these conditions, since it too reacts very rapidly with base. However, a steady-state concentration of 4 was detected spectroscopically. In the absence of base the decomposition of 4 (synthetic) to diphenylacetylene (8) was over four powers of 10 slower than that of its saturated analog (to trans-stilbene) despite the greater strain in 4. Photolysis of 4 resulted in a relatively rapid conversion into 8. With methoxide ion 4 underwent competitive first-order reactions to give methyl cis-1,2-diphenylethenesulfonate (6) and 8. Reaction of I with hydroxide ion in aqueous dioxane gave small amounts of cis- and trans-1-bromo-1,2-diphenylethylene (derived from 3) in addition to 6 (as the salt) and 8. Similar results were obtained with potassium t-butoxide in t-butyl alcohol. © 1968, American Chemical Society. All rights reserved.