60239-58-9Relevant articles and documents
Azide and Solvent Trapping of Electrophilic Intermediates Generated during the Hydrolysis of N-(Sulfonatooxy)-N-acetyl-4-aminostilbene
Novak, Michael,Kayser, Kelly J.,Brooks, Michael E.
, p. 5489 - 5496 (2007/10/03)
Hydrolysis of the carcinogenic title compound 1a in 5 vol % CH3CN-H2O, μ = 0.5, 20 °C at pH 7.2 in 0.02 M phosphate buffer, yields the rearranged material 3-(sulfonatooxy)-N-acetyl-4-aminostilbene (4) (23 ± 1%), threo-1,2-dihydroxy-1-phenyl-2-(4-acetamidophenyl)ethane (5) (57 ± 2%), and erythro1,2-dihydroxy-1-phenyl-2-(4-acetamidophenyl)ethane (6) (20 ± 2%) in the absence of added nucleophiles. Addition of N3- has no effect on the rate constant for decomposition of 1a (ca. 1.9 × 10-2 s-1), but generates a number of adducts that result from trapping of three different electrophilic intermediates. The ortho-N3 adduct 3-azido-N-acetyl-4-aminostilbene (7) is produced from trapping of the nitrenium ion 2. A fit of the product yield data as a function of [N3-] provides the ratio kaz/ks of 280 ± 10 M-1 for competitive trapping of 2 by N3- and H2O. The nucleophilic aromatic substitution product 7 is a minor reaction product. The predominant site of attack by N3- on 2 (ca. 85%) is at the β-vinyl carbon to produce the quinone imide methide 3b. Attack of H2O at the same site produces the analogous intermediate 3a. Both of these electrophilic species are competitively trapped by N3- and H2O with trapping ratios kaz′/ks′ for 3b of 107 ± 8 M-1 and kaz″/ ks″ for 3a of 39 ± 2 M-1. The reactivity patterns of 2 are unlike those of other N-arylnitrenium ions that undergo predominant nucleophilic aromatic substitution with nucleophiles such as N3-. The quinone imide methides that are produced by nucleophilic attack on the β-carbon of 2 react selectively enough with nonsolvent nucleophiles that they may be physiologically relevant.
