Elimination and addition reactions. Part 40. The insignificant effect of strain in higher order eliminations in 1,1-bis(phenylsulphonyl) carbanions with w-leaving groups

Rates of cyclisation of 1 ,I -bis(phenylsulphonyl) carbanions bearing distal leaving groups have been determined. The response of the system to solvent effects and to leaving group is similar to that in i n termolecu la r nu Cleo p h i I ic su bst i t u t i on. The system is very sensitive to the size of the ring formed; for iodides in ethanol the ratios for ring sizes 3: 4 : 5 : 6 : 7 are 1 : 1 .I x 10E-5: 1 .O x 10E-2: 1.6 x 1OE-6: 7.3 x 1OE-1O. The contribution of strain in the product to the enthalpy of activation is slight and inconsistent; the entropy of activation for cyclopropane formation is so favourable as to make this by far the most rapid process observed.