Thiophenoxide anion

Condensation of thiophenoxide anions with various fluonnated polychloro- or polybromoethanes gives fluoroalkyl phenyl sulfides [57, 52, 55], These formal substitutions involve fluonnated olefins as intermediates [52, 55], In the case of perhalogenated ethanes, the mechanism shows a similarity with that of dihalo-genodifluoroinethane [52] (equations 46 and 47)... 

In the case of thiophenoxide and dichlorodifluoromethane, such a reaction forms chlorodifluoromethyl carbanion, which dissociates to difluorocarbene and chloride anion. Difluorocarbene reacts with the thiophenoxide anion to form phenylthiodifluoromethyl anion. This unstable species reacts in two ways. (1) It abstracts chlorine from another molecule of dichlorodifluoromethane and forms chlorodifluoromethyl phenyl sulfide Y. (2) It reacts with hydrogen of water to form difluoromethyl phenyl sulfide Y. Product Y can also react with two molecules of thiophenoxide anion to give bis(thiophenyl)difluoromethane Y" [SO]. 

The reaction starts probably by elimination of the tertiary fluorine atoms. Thus, a bicyclic olefin is formed. Its double bond activates the four allylic fluorines for nucleophilic displacement by thiophenoxide anions to give l,4,5,8-tetrakis(phenylthio)perfluoro-A9 10-octalin. 

The ideal method of 7 -demethylation may turn out to involve the use of thiophenoxide anion in refluxing 2-butanone. Under these conditions bulhocapnine methothiophenoxide (LXXVI) is converted into the corresponding tertiary free base bulhocapnine (LXXVII), in 72% yield. The reaction mechanism is of the simple Sjj2 type, and consists of attack by the thiophenoxide anion on one of the iV-methyl groups 60). 

Cohen and coworkers have described the preparation of a-lithio ethers from a-sulfides by a mechanistically novel route in the presence of lithium (dimethylamino)naphthalenide. The reaction is postulated to proceed through the radical anion produced by single electron transfer (SET) and subsequent homo-lytic cleavage (loss of thiophenoxide anion) to give a radical. Further reduction of the radical then leads to the a-alkoxy carbanion. 

Selective N-dealkylation in the presence of N-aryl linkages may be induced by pyridine hydrochloride, and selective N-debenzylation by thiophenoxide anion. ... 

The drastic change in the reactivity of oxygen nucleophiles is also found in several other examples. Thiolate anions are classified as stronger nucleophiles than their oxyanionic counterparts (DeTar and Coates, 1974 Williams and Donahue, 1978). It was found, however, that towards PNPA in dimethyl-formamide the nucleophilic reactivity of thiophenoxide ion exceeds that of phenoxide ion when [H20] = ca. 1000 mM but the relative reactivity was sharply reversed below [H20] = 300 mM (Shinkai et al., 1979a). Therefore, phenoxide ion can be a much stronger nucleophile than thiophenoxide ion in very dry aprotic solvents. 

Of particular interest was the reaction of two equivalents of potassium phthalimide with PFB using 18-crown-6 in refluxing acetonitrile. This reaction with either small molecules or the polymeric analogs represents a novel approach to arylimide synthesis via PTC. After 4 hr. under nonoptimized PTC reaction conditions, disubstitution afforded the bisimide 6 in ca. 50% yield. This shows that phthalimide anion, a considerably poorer nucleophile than either the phenoxide or thiophenoxide, is a strong enough nucleophile in the presence of 18-crown-6 to displace aryl fluoride with facility, and demonstrates that the synthesis of polyimides, an important class of thermally stable polymers, is feasible by this PTC polycondensation route. 

It has recently been shown that alkyl sulfoxides are good solvents for transition metal halides, and many adducts can be isolated 42, 84, 167, 227, 231). Nickel perchlorate takes up six dimethyl sulfoxide ligands, but the chloride apparently only three. It has been shown from the reflectance spectrum and from the high magnetic moment 42) that this compound should be formulated as [Ni(DMSO)6][NiCl4], in which the anion is tetrahedral. Infrared spectra 43, 127) show that the dimethyl sulfoxide coordination is through oxygen. Similar compounds are found with tetrahydro-thiophenoxide 84) ... 

Chiral a,(3-unsaturated sulfoxides also produce predominately one diastereomer on addition of heteronucleophiles (equation 96).104 Kinetic protonation of the anion (440 Scheme 59), generated by addition of thiophenoxide to the nitroalkene (233), followed by trapping with formaldehyde, produced a 87 13 mixture of diastereomers favoring (441).10S Finally, the use of high pressure can increase the dia-stereoselectivity of the addition of amines to chiral crotonates.,06a... 

Taber (42) and Kondo and co-workers (43) have found the stereospecific opening of J 2T + V22 with thiophenoxide. Using phenyl selenide anion as the reagent, Isobe and collaborators (44) discovered the conversion 123 124. 

Cycttzation of dianions of bis(diphenyl thiocetals). Treatment of I with 2-4 equiv. of methyllithium and of TMEDA results in formation of 2 (major product) and 3. The paper presents evidence that these cyclizations involve an intermediate dianion, which loses a thiophenoxide ion to give an anionic sulfur-stabilized carbene. 

This change is a result of a change in the state of the reacting anion from free thiophenoxide to a solvent-separated sodium thiophenoxide ion-pair complex. 

In DMSO and in DMF the anion is only weakly solvated. In MeOH the hydrogen bonding to the thiophenoxide ion lowers the electron density on the sulphur atom of the free ion in a similar way that the sodium ion does in the ion-pair complex and therefore the relative changes of the secondary (kn/kD)a KIE in MeOH with increase of PhSNa concentration are smaller in this polar solvent than in the dipolar aprotic solvents, DMSO and DMF. The interaction of MeOH with the sodium ion probably plays a certain role also. 

Ring closure to cyclobutanes and cyclopentane-s The synthesis of cyclo-propanones by elimination of lithium thiophenoxicMe with this base has been extended to similar syntheses of functionalized cyclob tanes and cyclopentanes, as shown in equations (I) and (II), When extended to synthesis of a cyclohexane derivative, this method resulted in a very low yield. One possible mechanism is formation of a dianion followed by loss of thiophenoxid e ion to give a carbene-anion, which cyclizes with loss of the second thiophenoxide ion. 

Thiophilic agents, such as trimethyl phosphite, phosphorous triamides, secondary amides (piperidine, diethylamine) or anionic thioderivatives (thiophenoxide, sodium sulfide) are commonly used2. They differ in their efficiency of trapping the sulfenate ester in the following order1 ... 

The reactions of bases with borylstannylalkanes generally lead to cleavage of the tin moietyand lithium thiophenoxide is especially specific. It is of interest that the reaction of fluoride anion with di-mesitylboryl(trimethylsilyl)alkanes also gives a-boryl carbanions, thus obviating the need to use organo-metallics. ... 

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