25273-25-0Relevant academic research and scientific papers
Application of Mechanistic and Transition-State Indicators to endo and exo-2-Norbornyl Arenesulfonates. Definition of a new Mechanistic Indicator
McManus, Samuel P.,Smith, Maurice R.,Shankweiler, Jean M.,Hoffman, Robert V.
, p. 141 - 148 (2007/10/02)
We have mechanistically classified endo- and exo-2-norbornyl arenesulfonates by using two common probes: the effect on rate of added thiourea and rate correlation in aqueous ethanol and trifluoroethanol.Interestingly, the exo isomer is improperly classified by each of these probes because of medium-dependent ion-pair return.In search of better mechanistic indicators, pseudo-first-order solvolytic rates and products have been determined for a series of endo- and exo-2-norbornyl arenesulfonates.Using these and literature data, we have compared these substrates with others by plotting α-deuterium isotope effects against β1gMe values determined for a series or arenesulfonates in the same or a similar solvent.The use of this type of plot as a heuristic method for distinguishing k8 and kΔ substrates is discussed.Finally, our product studies are consistent with the involvement of solvent-seperated ion pairs in the solvolysis of 2-norbornyl arenesulfonates.Different alcohol-ether product ratios for the isomeric esters in consistent with dual pathways for product formation with the endo substrates.
Solvomercuration-Demercuration. 11. Alkoxymercuration-Demercuration of Representative Alkenes in Alcohol Solvents with the Mercuric Salts Acetate, Trifluoroacetate, Nitrate, and Methanesulfonate
Brown, Herbert C.,Kurek, Joseph T.,Rei, Min-Hon,Thompson, Kerry L.
, p. 2551 - 2557 (2007/10/02)
The alkoxymercuration-demercuration of seven representative olefins with the mercuric salts acetate, trifluoroacetate, nitrate, and methanesulfonate, in methyl, ethyl, isopropyl, and tert-butyl alcohols was examined.Mercuric acetate was effective only in methanol and ethanol.On the other hand, mercuric trifluoroacetate was effective in all four solvents, giving in most cases high yields of the corresponding ethers.Both mercuric nitrate and mercuric methanesulfonate were effective in methanol, ethanol, and 2-propanol.However, in several cases poor selectivity for the ether was observed, as evidenced by the formation of significant amounts of side products.Both electronic and steric effects are important factors in the reaction.Moreover, the structure of the olefin has a pronounced effect, both on the types of oxymercurials formed and on their stability to the reaction conditions.
Norpinyl-Norbornyl Rearrangements: Bicycloheptane, 4-Methyl- and 6-Methylbicycloheptane Derivatives
Kirmse, Wolfgang,Siegfried, Rainer,Wroblowsky, Heinz-Juergen
, p. 1880 - 1896 (2007/10/02)
Norpinyl-norbornyl rearrangements have been induced by solvolysis of the 2-norpinyl nitrobenzoates 15b, c and by decomposition of norpinane-, 4-methylnorpinane-, and 6-methylnorpinane-2-diazonium ions (19, 49, 64, 65).No fragmentation to monocyclic cations was observed.The yield of norpinyl products was minimal in water (s processes).With 64 and 65, migration of the bridge trans to the leaving group predominated strongly.The rearrangements afforded exo-2- and endo-2-norbornyl products in comparable quantities.The exo/endo rates depended on the nucleophilicity of the solvent but were little effected by methyl substitution at the migrating carbon.We propose the 7-bridged norbornyl cation (21) as the endo-selective intermediate which rearranges to the exo-selective 6-bridged (or rapidly equilibrating) norbornyl cation (22, 23) in competition with solvent capture.Ion-pair collapse (cf. 15b) accentuates the endo-selectivity.However, ion pairing cannot be the only source of endo-2-norbornyl products, as shown by the deamination reactions in water.
Hindered Nucleophilic Displacement (SN2) Reactions of 2exo- and 2endo-Norbornyl Derivatives. Norbornane Series 4.
Grob, Cyril A.,Lutz, Erich
, p. 153 - 160 (2007/10/02)
The reactions of 2exo- and 2endo-norbornyl bromide (1 e and 2 e, respectively) in 90 percent ethanol with a large excess of potassium hydroxide, and 2exo-norbornyl-p-toluenesulfonate (1 g) with excess sodium thiophenolate in methyl cellosolve, have been studied.They obey the first order rate law and are zero order with respect to the base-nucleophile.However, the ratio of 1,2- and 1,3-elimination to exo-substitution products depends strongly on the base-nucleophile concentration.The extreme inertness of 2-norbornyl derivatives in displacement reactions is due to severe steric hindrance of rearside nucleophilic attack, a feature they have in common with other bi- and tricyclic molecules bearing nucleofugal groups adjacent to one or two bridgehead atoms.
