- Clarification of the stereochemical course of nucleophilic substitution of arylsulfonate-based nucleophile assisting leaving groups
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(Chemical Equation Presented) Secondary alcohols modified as tosylates, PEG-sulfonates, or quisylates undergo inversion of configuration at the reacting center when treated with lithium halide in acetone at reflux, where the PEG-sulfonates and quisylates are substantially more reactive. In sterically hindered cases, elimination is a competing process. In contrast, when treated with TiCl4, simple secondary sulfonates give chloride products with partial inversion of configuration. Any observed retention of configuration in a given alkyl sulfonate substrate under these conditions is likely due to neighboring group participation or diastereoselective attack on a carbocation (or ion pair) rather than an SNi mechanism.
- Braddock, D. Christopher,Pouwer, Rebecca H.,Burton, Jonathan W.,Broadwith, Phillip
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supporting information; experimental part
p. 6042 - 6049
(2009/12/24)
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- Formation of Olefins via Pyrolysis of Sulfonate Esters
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Esters of 8-quinolinesulfonic acid and 2-pyridinesulfonic acid were synthesized from alcohols and the acid chlorides.The secondary esters decomposed cleanly at moderate temperatures to give olefins in hight yield.Product studies were consistent with carbocation formation and abstraction by a ring nitrogen to give olefin.The importance of a basic group was confirmed by pyrolysis of a series of para-substituted cyclohexyl benzenesulfonates, p-XC6H4SO3R.The compounds with X=NHEt and NHCOMe reacted cleanly to give olefin in good yield.When X = NO2, Br, CH3, or OCH3, olefin was formed in low yield along with considerable amounts of tar.
- Corey, E. J.,Posner, Gary H.,Atkinson, Richard F.,Wingard, Astrid K.,Halloran, Daniel J.,et al.
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p. 389 - 393
(2007/10/02)
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