82784-21-2Relevant academic research and scientific papers
Sulfonyl esters. 3. The formation of sulfone-sulfonates in the reactions of aryl methanesulfonates with sodium borohydride
Baum, James Clayton,Durkin, Kathleen Anne,Precedo, Laura,O'Blenes, Stacy Brian,Goehl, John Edward,et al.
, p. 2127 - 2135 (2007/10/02)
Sodium hydride reductions of aryl methanesulfonates afford dimeric sulfone-sulfonate esters as well as products arising from SO bond rupture.SO bond rupture becomes more competitive as the LUMO energy of the sulfonate ester declines.Exploration of the chemistry of a sulfone-sulfonate ester revealed a complex novel reaction that resulted in the formation of, inter alia, a dichloromethanesulfonate ester and a trichloromethanesulfonate aster.The first succesful approaches to the synthesis of the heretofore unknown trichloromethanesulfonates and dichloromethanesulfonates are reported.Key words: sodium hydride reductions, sulfenes, sulfone-sulfonate esters.
Intramolecular Reactions. Part 12. Ring Size and Leaving Group Effects on Inter- and Intra-molecular Nucleophilic Substitution by Carbanions
Bird, Roger,Griffiths, Gwerydd,Griffiths, Gwynfor F.,Stirling, Charles J. M.
, p. 579 - 584 (2007/10/02)
In cyclisations of aryl ο-halogenoalkyl ketones to aryl cycloalkyl ketones with base, cyclopropanes are formed up to 23000 times faster than cyclopentanes.Hydrogen-deuterium exchange experiments and very low bromide-chloride ratios (1.9) for three-membered ring formation are consistent with rate-determining deprotonation of the ketone.By contrast, in five-membered ring formation, hydrogen-deuterium exchange adjacent to the carbonyl group occurs much faster than cyclisation and the chloride-bromide ratio is 'normal' at 99.In formation of arylsulphonylcyclopropanes from arylsulphonylpropyl arenesulphonates, the Hammett ρ value for the leaving group is +1.7, and for intermolecular substitution by bis-sulphonyl stabilised carbanions, +1.2.Attempts to obtain ρLG values for five-membered ring formation were frustrated by competing intermolecular reactions.The results are discussed against the background of previous work on ring formation by intramolecular nucleophilic substitution.
