Nucleofugality of the Sulfinate Group in Carbocation-Forming Processes

Article abstract of DOI:10.1021/jo00225a017

The solvolytic reactivity of a variety of sulfones and sulfinate esters has been determined which allows one to place the sulfinate leaving group in a relative nucleofugality scale.Cumyl trifluoromethyl sulfone (1) reacts in a variety of solvents to give substitution products.The m_OTs value of 0.82 is indicative of the involvement of the cumyl cation (9) formed in k_c process.In terms of rate, 1 is 170 times less reactive than cumyl chloride but 286 times more reactive than cumyl p-nitrobenzoate.The analogous cumyl methyl sulfone (2) and cumyl phenyl sulfone (3) solvolyze approximately 10⁷ times more slowly than 1.The sulfinate esters cumyl methanesulfinate (6) and cumyl p-toluenesulfinate (7) are considerably more reactive than the analogous sulfones.Methanolysis of 6 was also subject to acid catalysis, where a mechanism analogous to the A_AL1 mechanism of hydrolysis of esters of carboxylic acids was suggested.The less hindered α-phenethyl trifluoromethyl sulfone (4) and p-methoxybenzyl trifluoromethyl sulfone (5) solvolyzed at rates that approached those of the analogous p-nitrobenzoates.This was indicative of the importance of relief of steric congestion in solvolyses of the more hindered tertiary sulfone 1.