Sulfonamide anion

The selective reaction of anionic 3,6-dichloro-4-sulfanilamidopy-ridazine with excess methanolic methoxide at the 3-position is another indication of the absence of major steric effects in most nucleophilic substitutions, as a result of the direction of nucleophilic attack (cf. Section II, A, 1). The selectivity at the 3-position is an example of the interaction of substituent effects. The sulfonamide anion deactivates both the 3-chloro (ortho direct deactivation) and... 

Despite the utility of chloroaluminate systems as combinations of solvent and catalysts in electrophilic reactions, subsequent research on the development of newer ionic liquid compositions focused largely on the creation of liquid salts that were water-stable [4], To this end, new ionic liquids that incorporated tetrafiuoroborate, hexafiuorophosphate, and bis (trifiuoromethyl) sulfonamide anions were introduced. While these new anions generally imparted a high degree of water-stability to the ionic liquid, the functional capacity inherent in the IL due to the chloroaluminate anion was lost. Nevertheless, it is these water-stable ionic liquids that have become the de rigueur choices as solvents for contemporary studies of reactions and processes in these media [5],... 

Feldman reported a route to dihydropyrroles, pyrroles, and indoles via the reaction of sulfonamide anions with alkynyliodonium triflates <96JOC5440>. Thus, upon nucleophilic addition of the anion of 91 to the p-carbon of the alkynyliodonium salt, the alkylidene carbene 92 is generated which can the undergo C-H insertion to the desired product 93. 

Vogtle has developed this approach further and employed a series of anionic templates to prepare rotaxanes (instead of the neutral template in the above reaction) [65-67]. In this approach a phenolate, thiophenolate or sulfonamide anion is non-covalently bound to the tetralactam macrocycle (46) forming a host-guest complex via hydrogen bonding (see Scheme 21). 

The allenylindium intermediates are prepared by treatment of the aziridines with Pd(PPh3)4 in THF-HMPA containing 1 equivalent of water. In the presence of iso-butyraldehyde the expected adducts were formed with excellent diastereoselectivity (Tables 9.56 and 9.57). Interestingly, the reaction did not proceed in the absence of water. It is suggested that water is needed to protonate the sulfonamide anion of the initially formed allenyl palladium species (Eq. 9.150). 

Sulfonyl azides are exceptional in that they do not normally give triazoles with activated methylene compounds nucleophilic attack by the carbanion is usually followed by loss of the sulfonamide anion, giving a diazo compound as the product. Possible mechanisms for the reaction are illustrated (Scheme 8) for diethyl malonate. Attack of the carbanion on the terminus of the azide gives the anion of the linear triazene (1). 

Sulfonamide anions react with a variety of electrophiles, as was showcased in CHEC-II(1996). One example from the recent literature involves the reaction of bicyclic sulfonamide 142 with trisyl azide to afford approximately a 2 1 mixture of diastereomers 143 and 144 (Equation 20) <2003T7047>. 

A variety of five-membered nitrogen heterocycles can be prepared efficiently by inter- or intramolecular addition/cyclizations of sulfonamide anions with alkynyliodonium salts. The intermolecular variant employs the combination of the amides 172 or anilides 174 with propynyl(phenyl)iodonium triflate (Scheme 65) [131,132]. The yield of dihydropyrroles 173 in this cyclization is extremely sensitive to the nature of the protective group P the tosyl group in 172 proved... 

The mechanism of this last reaction may be postulated as shown in Scheme 52. Here, the initial nucleophilic attack by the sulfonamide anion (129) is followed by protonation of the intermediate and attack by the chloride anion to yield two moles of the sulfamoyl chloride (125). A wide range of sulfamoyl derivatives can be prepared by nucleophilic displacement of the chlorine atom in sulfamoyl chlorides (125). Examples include condensations with ureas, alcohols, compounds containing acidic hydrogens and nitrogen heterocycles to give the corresponding sulfamoyl derivatives (130)-(133) (Scheme 53). 

The enolate attacks the oxygen atom of 273 in an unusual SN2 reaction at oxygen 276. The leaving group is the sulfonamide anion, which is why a sulfonamide is necessary. The anion returns 277 to form the original imine 272 and ejects the anion 278 of the a-hydroxy-carbonyl compound 275. 

Estersulf. [Climax Performance] Sulfonamide anionic ester. 

The neutral inhibitors of CA like sulfonamide, such as acetozola-mide, bind to Zn " -[12]aneN3 in a 1 1 stoichiometry as determined from 4-NA hydrolysis and isolation of Zn-sulfonamide-pendant [12]aneNa complex. UV-spectral data indicated coordination of sulfonamide anion to Zn -[12]aneN3. The X-ray crystal structure of the Zn-imidazole-pendant [12]aneN3 complex revealed a five-coordinate TBP structure with imidazole N at an equatorial position and a Cl counter ion at an apical position. Neither this complex nor its deprotonated imidazolate form (pi a 10.3) hydrolyzes 4-NA in aqueous solution, indicating the inhibitory action of imidazole similar to that for CA. 

These i l anion complexation constants for the zinc(II) macrocyclic triamine complexes with various aromatic sulfonamides exhibit a trend paralleling that reported for suggesting a similar inhibition mechanism [i.e., the deprotonated sulfonamide anions can coordinate to the zinc(II) in aCA-active center].The effectivemolarity of the pendant sulfonamide in the model complex may be viewed as the noncoordinating contributions to bring the inhibitors to the zinc(II) center ofCA. 

It is well documented in the literature that the sulfonamide anion (SO2NH") specifically binds to the carbonic anhydrase and inhibits its activity. This sulfonamide anion forms a complex with zinc cation at the active... 

Despite the precedence for lower selectivity, Ellman and co-workers realized that addition of a Grignard reagent proved to be more efficient (745). After Grignard reagent addition to ent- 91, spontaneous cyclization to azepine 201 occurred upon formation of the nucleophilic sulfonamide anion (Scheme 4.3). It is interesting to mention that because Grignard addition provides the opposite diastereoselectivity in comparison to Rh(I)-catalyzed addition, the other enantiomer of A-f-butanesulfinyl imine (enf-197) had to be applied. 

Acidity of Sulfonamides (Section 18.2) Sulfonamides 9 10) dissolve in aqueous NaOH by forming water-soluble salts. The sulfonamide anion is stabilized by delocalization of the negative charge onto the two O atoms. 

Scheme 103. The Hinsberg reaction. Alkylation at nitrogen of benzenesulfonamide with bromoethane (CHjCH2Br) produces Af-ethylbenzenesulfonaniide and, on repetition of the process, NA -diethylbenzenesulfonamide. An alternative process, the reaction of benzenesul-fonyl chloride with ethanamine (CH3CH2NH2) to produce iV-ethylbenzenesulfonamide and subsequent alkylation of the latter via formation of the sulfonamide anion and reaction of that anion with bromomethane (CHsBr) is also provided.

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