Thiophenols anion

The role of the quaternization of the azasubstituent in the nucleophilic substitution at 2-halogenothiazoles is in fact emphasized by the reactivity of 2-halogenothiazoles with undissociated thiophenol (35), which proceeds faster than the corresponding reaction of 2-halogenothiazoles with thiophenolate anion, through the pathways shown in Scheme 6. Moreover, the 4-halogenothiazoles do not react with undissociated thiophenols, while the 5-halogenothiazoles react well (48). 

The much steadier anion-radicals of 4-bromobenzophenone are able to diffuse into the volume without disintegration. In the volume, they lose the bromine anion and form the corresponding radicals, which are intercepted with the thiophenolate anions. The product of so-to-speak nucleophilic substitution is formed. 

Fig. 4. Relative reactivities of cyclopropylideneacetates 1-3 towards thiophenolate anion compared to 3,3-dimethylacrylate [5b,c, 15b, 27]...

Thus, in a competition experiment, the chloro ester 1 -Me reacted with thiophenolate anion 216 times faster than methyl 3,3-dimethylacrylate (Fig. 4). Part of this enhanced reactivity is due to the a-chloro substituent in 1-Me, as the parent methyl cyclopropylideneacetate (3-H) reacts only 18 times faster than 3,3-dimethylacrylate, while 3-SPh reacts 5160 times more rapidly [5b,c, 15b,271. 

Poly(arylenethioether phenylquinoxaline)s have been prepared from the reaction of a bis(chloroquinoxaline) compound with 4,4 -dimercaptodiphenyl ether [19]. The polymer of structure 4 had an unusually high intrinsic viscosity of 4.0 dL/g, a Tg of 243 °C and good solubility in NMP and chloroform. The greater nucleophilicity of the thiophenolate anion versus the phenolate anion allowed the formation of high molecular weight polymer from the... 

Addition of the thiophenolate anion to the / -carbon atom of the enone is the chirality-determining step it is, at the same time, rate-determining. The transition state is a ternary complex comprising the catalytic base in the protonated form, the thiophenolate anion, and the enone. The last is activated to nucleophilic attack by hydrogen-bonding to the catalysts / -hydroxy group. The chiral cinchona bases thus act as bifunctional catalysts. 

Mills et al,239 first observed that the 3-methylbenzothiazolium cation (78 R = H) may be titrated in one step with two equivalents of base to give the ring-opened thiophenol anion (80 R = H). This anion is readily air-oxidized in basic solution to the disulfide. The 2,3-dimethylbenzo-... 

Dequatemization of azolium quaternary salts initially involved pyrazol-ium compounds, which could be pyrolyzed in vacuum at ca. 200°C (66AHC417). The use of thiophenolate anion under phase transfer catalysis proved to be an excellent method of obtaining pyrazoles and indazoles in high yield from their corresponding quaternary salts [78CR(C)439]. The thermal descomposition of imidazolium quaternary salts has been studied by Grimmett et al. (77AJC2005). 

Certain malononitrile, ethyl cyanoacetate, alkoxide and thiophenolate anions behave similarly and give the requisite acrylic acid derivatives or tautomers thereoF Moreover, the reaction of various carboxylates, amides, amines (but not ammonia, see below) thioamides, ynamines, pyridines and j5-acylenamines give products which are rationalized in terms of an initial 1,2-addition . ... 

Vesicles of dioctadecyldimethylammonium chloride (DODAC) are relatively resistant to permeation of organic anions at 25 °C, at imposed exolendo pH gradients of 3 units. Thiophenolate anions, for example, can not be oxidized by o-iodosobenzoate if both reagents are encapsulated in DODAC vesicles (Figure 4.20). Reaction occurs immediately after addition of some ethanol. 

The benzenethiolato ligand has been coordinated to a rhodium center in the complex Rh(SPh)[P(CH3)3]3. This complex, prepared from sodium thiophenolate and Rh(Cl)[P(CH3)3]3, reacts smoothly with air either in the solid state or in solution (155) to form the yellow dioxygen complex Rh(02)(SPh)[P(CH3)3]3. In a similar fashion, a mixture of Rh[P(CH3)3]4HCl and the thiophenolate ion reacts with air in solution to form the dioxygen complex The analogous complex with para-methoxythiophenolate can also be formed in this manner. Although the mechanism of formation of the dioxygen complexes directly from the thiophenolate anion and Rh[P(CH3)3]4 Cl is not fully understood, the initial formation of a rhodium(I)-thiophenolato complex such as Rh(SR)[P(CH3)3l , n = 3 or 4, is possible the extreme sensitivity of the intermediate thiophenolate complex prevented its isolation. 

Alkylsulfinyl groups at position 2 of an activated thiophene undergo facile nucleophilic displacement by alkyl or aryl mercaptans (Scheme 116) <88T5921>. However, if thiophenolate anion is used in this reaction instead of neutral thiophenol, the products are completely different. 

The relatively stable (arylsulfonylmethyl)iodonium salts 763 (Section 2.1.9.5) are efficient electrophilic alkylating reagents towards various organic nucleophiles (thiophenolate anion, amines, pyridine, triphenyl phosphine and silyl enol ethers). All these reactions proceed under mild conditions and selectively afforded the appropriate product of alkylation along with iodobenzene as the by-product (Scheme 3.299) [1016]. 

The mixed phosphonium-iodonium ylides (Section 2.1.10.1), such as the tosylate 796, represent a useful class of reagents that combine in one molecule the synthetic advantages of a phosphonium ylide and an iodonium salt [1091-1100]. Specifically, phosphorane-derived phenyliodonium tosylate 796 reacts with soft nucleophiles, such as iodide, bromide, benzenesulfinate and thiophenolate anions, to form selectively the respective a-functionalized phosphonium ylides 797 (Scheme 3.315), which can be further converted into alkenes (e.g., 798) by the Wittig reaction with aldehydes [1092]. The analogous arsonium-iodonium ylides have a similar reactivity toward nucleophiles [1091, 1094, 1101]. 

Taber has outlined a route to the prostaglandin intermediate (64), with the correct stereochemistry at several important positions, which is based on opening of the cyclopropane ring in (63) with thiophenol anion, followed by oxidation, and reductive rearrangement of the resulting sulphoxide (Scheme 15). ... 

The same structural type of dimer involving a central four-membered ring core has been established for bulky thiolate ligands such as the 2,4,6-tris(isopropyl)-thiophenolate anion [138]. 

However, disappointingly poor selectivities were observed with sulfur nucleophiles. The high reactivity of the sulfur nucleophiles resulted in rapid nucleophilic displacement reactions relative to the epimerisation process and this may explain the lack of selectivity (Scheme 1.12). Moreover, the results of DKR reactions using sulfur nucleophiles are in agreement with the observed dichotomy methyl thioglycollate and benzyl mercaptan behaved similarly to amines, whereas thiophenol (which should be in the form of the thiophenolate anion under the reaction conditions used) showed the same preferential reactivity as the metallated nucleophiles. 

This system serves as the prototype for aryl thiyl radicals. Measurements of the high g tensor values and anisotropy observed in ESR [36] was interpreted to indicate a high degree of localization of the unpaired electron on the sulfur atom. This conclusion has been strongly reinforced [37] by experimental observations of a high rate constant for second order decay implying rapid spin relaxation, the formation of diphenyldisulfide as dominant combination product rather than any ring-bonded products and the close similarity of vibrational frequencies in the radical with those of its parent thiophenolate anion and thiophenol species. Further support comes from measurements [38] of the pXg, reduction potential, and electron transfer kinetics. 

An example of cZne-substitution on a thiophene is the reaction of 3,4-dinitrothiophene with thiophenolate anion in methanol, in a multistep sequence, to produce 2-arylsulfanyl-4-nitrothiophene 89 (Scheme 130) [186]. 

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