Phenylthiol

In the former (Ingold) nomenclature this was called the SRN1 mechanism (see IUPAC, 1989a). This scission may consist of two steps, forming first an aryldiazenyl radical and the phenylthiolate radical (see Sec. 8.6). 

Bachman, R.E., Bodolosky-Bettis, S.A., Glennon, S.C. and Sirchio, S.A. (2000) Formation of a novel luminescent form of gold(I) phenylthiolate via self-assembly and decomposition of isonitrilegold(l) phenylthiolate complexes. Journal of the American Chemical Society, 122, 7146-7147. 

Derivatives with various substituted sulfonamides have been developed and used to form enolates from esters and thioesters.137 An additional feature of this chiral auxiliary is the ability to select for syn or anti products, depending upon choice of reagents and reaction conditions. The reactions proceed through an acyclic TS, and diastereoselectivity is determined by whether the E- or Z-enolate is formed.138 /-Butyl esters give A-enolates and anti adducts, whereas phenylthiol esters give syn adducts.136... 

Reaction sequence E removed an extraneous oxygen by Sml2 reduction and installed an oxygen at C(15) by enolate oxidation. The C(l) and C(15) hydroxy groups were protected as a carbonate in Step E-5. After oxidation of the terminal vinyl group, the C-ring was constructed by a Dieckmann cyclization in Step F-4. After temporary protection of the C(7) hydroxy as the MOP derivative, the (1-ketoestcr was subjected to nucleophilic decarboxylation by phenylthiolate and reprotected as the BOM ether (Steps F-5, F- 6, and F-7). 

An interesting multicomponent domino free radical reaction in which five new bonds are formed in one operation has recently been applied in the total synthesis ofyingzhaosu A by Bachi and coworkers. Thus, a 2,3-dioxabicyclo[3.3.1]nonane system reacts with phenylthiol and 2 equiv. of molecular oxygen in the presence of AIBN, which under irradiation with UV light led to a diastereomeric mixture of en-doperoxide-hydroperoxides [127]. 

Analogous monomeric iminoboranes which are fully alkylated at the B-atoms have also been prepared 27). Treatment of bromosubstituted iminoboranes with phenylthiol, however, also causes the B-bonded halogen to be replaced by thiophenyl groups ir> (Eq. 44). 

The chlorodifluoromethylated ketone 130 proved to be a valuable substrate for promoting SrnI subtitution reaction with sodium phenylthiolate and to generate a new a-(phenylthio)-a,a-difluoroacetophenone derivative 131 (Equation 57) <2001TL3459>. Upon treatment with nitronate anions under classical SrnI reaction conditions or MW irradiation, 6-chloromethyl-5-nitro-imidazo[2,l- ]thiazole 132 yielded 5-nitroimidazothiazoles bearing a trisubstituted ethylenic double bond at the 6-position (Equation 58) <2001SC1257>. 

Methyl-3-nitro-l-nonene (427) and sodium phenylthiolate show different modes of behaviour under different conditions in HMPA the product 428 of attack at the less hindered carbon atom is obtained, whereas in the presence of Pd(PPh3)4 the isomer 429 is produced457. 

As a final example in this section, we may consider the i/ .vo-di spl acernen l of the nitro group itself. Liu and Zhao68 have investigated the substitution of the nitro group in a series of 4-nitrobenzoate esters by the phenylthiolate anion. Here the process again involves radical species, but now it is the radical anions of the nitro compounds which are observed as well as the thiophenoxyl radical which could be trapped. 

Structurally rather complicated target molecules can be synthesized with the aid of thi-olate 1,6-addition reactions to acceptor-substituted dienes as well. For example, a richly functionalized proline derivative with a 2,4-pentadienal side chain was converted into the corresponding 6-phenylthio-3-hexen-2-one derivative by 1,6-addition of phenylthiolate, treatment of the adduct with methyl lithium and oxidation (equation 46)127. The product was transformed into acromelic acid A, the toxic principle of clitocybe acromelalga ichimura. Similarly, the 1,6-addition reaction of cesium triphenylmethylthiolate to methyl 2,4-pentadienoate served for the construction of the disulfide bridge of the macrobicyclic antitumor depsipeptide FR-901,228128. 

Concomitant C-Si cleavage by tetra-n-butylammonium fluoride and extrusion of a phenylthiolate anion from ot-trialkylsilyldisulphides provides a route to reactive thioaldehydes [44],... 

A reported procedure based on lithium diisopropylamide induced double elimination of ethanol from bromoacetaldehyde diethyl acetal also was not very effective for the large scale preparation of phenylthioacetylene.8 Another more recent synthesis of the title compound relies on the reaction of dimethyl(chloroethynyl)carbinol with an alkali metal phenylthiolate, followed by... 

Many reactions demonstrate a high activity of the phenylthiolate ion in trapping aryl radicals and inability of the phenolate ion to do so. Thus, the phenylthiolate ion acting on 5-chloro-2//, 3//-benzo[b]thiophenedione-2,3 produces the substitution product (in anion-radical form), whereas the phenolate ion initiates only the reductive dechlorination (Ciminale et al. 1978 Scheme 4.2). 

The mechanism of the reaction depicted in Scheme 4.6 differs from the Sf.,1 or Sf.,2 mechanism in that it involves the stage of one-electron oxidation-reduction. The impetus of this stage may be the easy detachment of the bromine anion followed by the formation of fluorenyl radical. The latter is unsaturated at position 9 near three benzene rings that stabilize the radical center. The radical formed is intercepted by the phenylthiolate ion. This leads to the anion-radical of the substitution product. Further electron exchange produces the substrate anion-radical and final product in its neutral state. The reaction consists of radical (R)-nucleophilic (N) monomolecular (1) substitution (S), with the combined symbol Sj j l. Reactions of Sj j l type can have both branch-chain and nonchain characters. 

As seen, the direct snbstitntion of the arylthio moiety for chlorine is observed only for the 4-nitro derivatives. The optically active snbstrate gives the racemic snbstitntion product on the reaction with phenylthiolate ion (Scheme 7.71). 

The passage from a stepwise (the phenylthiolate ion as a nucleophile) to a concerted mechanism (the nitropropanate ion as a nucleophile) is a consequence of the low driving force offered by the poor electron-donor properties of the nucleophile. 

The scope of Michael additions with catalysts containing cyclohexane-diamine scaffolds was broadened by Li and co-workers [95]. When screening for a catalyst for the addition of phenylthiol to a,p-nnsatnrated imides, the anthors fonnd that thiourea catalyst 170 provided optimal enantioselectivities when compared to Cinchon alkaloids derivatives (Scheme 41). Electrophile scope inclnded both cyclic and acyclic substrates. Li attributed the enantioselectivity to activation of the diketone electrophiles via hydrogen-bonding to the thiourea, with simultaneous deprotonation of the thiol by the tertiary amine moiety of the diamine (170a and 170b). Based on the observed selectivity, the anthors hypothesized that the snbstrate-catalyst... 

Exposure of thianthrene to Na/NH3(liq) caused cleavage of the ring phenylthiol and diphenyl disulfide were the observed products (61YZ13). 

The synthetic utility of the allyl sulfoxide-allyl sulfenate rearrangement is as a method of preparation of allylic alcohols.184 185 The reaction is carried out in the presence of a reagent, such as phenylthiolate or trimethyl phosphite, which reacts with the sulfenate to cleave the... 

After oxidation of the vinyl group, the C ring is constructed by a Dieckmann cyclization. The resulting jS-keto ester is subjected to nucleophilic decarboxylation by phenylthiolate [step F (4-6)]. 

Thiol anions normally add reversibly to uracil derivatives <1991T4361>, although stable adducts can be isolated when the intermediate enolate is trapped with an added electrophile <2006JHC1095>. Thus, the addition of lithium phenylthiolate to 5-fluoro-l,3-dimethyluracil 457 in the presence of benzaldehyde gave a 46% yield of the adduct 458 as a mixture of only two diastereomers <2006JHC1095>. 

Zinc and hydrochloric acid decompose 5-amino-3-phenylthio-l,2,4-thiadiazole with evolution of hydrogen sulfide and phenylthiol.86... 

Table 5. Po y(phenylsulfany )fluorobenzenes by Multiple Phenylthiolation of Polyfluorobenzenes54...

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