- Catalysis of Sulfonate Ester Hydrolysis by Intramolecular Amide Group Assistance.
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Kinetics of the alkaline hydrolysis of aryl 2-(acylamino)benzenesulfonates (1, X=OAr) obey the equation kobs=(Ka+kb->/(1++>/Ko).Hammett equations correlate the parameters ka, kb, and Ka for variation in both amido and leaving phenolate substituents.The values and sign of the ρ values together with entropy of activation data, reactivity trapping, and oxygen-18 incorporation are consistent with the formation of an intermediate benzoxathiazine S,S-dioxide (2).The ka term involves intramolecular attack of the amido anion.The kb term is consistent with a specific anion effect on ka.Regular bimolecular BAc2 mechanisms for ka and kb are not consistent with the high observed reactivity of these parameters.
- Thea, Sergio,Guanti, Giuseppe,Hopkins, Andrew R.,Williams, Andrew
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p. 3336 - 3341
(2007/10/02)
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- The Pyrolysis of 2-Azidobenzoates. A New Synthesis of Carbazoles and Other N-Heterocycles
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The spray pyrolysis of aryl 2-azidobenzoates yields carbazoles, involving a rearrangement whereby the nitrogen of the product is attached to the aryl 1-carbon, a process involving a spiro 6-membered intermediate.When the aryl ortho-positions were both alkyl substituted the product was ab acridan instead.With an ortho-carboxylate, acridone formation competed with that of carbazole.When the CO-O group of the substrate was replaced by O-CO, CO-S, CO-NPh, or SO2-O the pyrolysis was ineffective.Benzyl 2-azidobenzoates, however, pyrolysed to yield 1-benzyl-2,1-benzisoxazolones by an unprecedented C-O insertion reaction of the intermediate nitrene.
- Clancy, Michael G.,Hesabi, Massoud M.,Meth-Cohn, Otto
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p. 429 - 434
(2007/10/02)
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