Thioether-substituted compounds

A number of cyclic imides, such as uracil (11), can be used in conjunction with a nitrogenous base.64 These compounds are added to hydroxylamine developer formulations. Several thioether-substituted 2,4- or 4,6-dihydroxypyrimidines, such as (12), are useful.65 Thioether-con-taining carboxylic acids can be used in the preparation of electrically conducting transferred silver images. These include 3-thiapentanoic acid, 3-thiapentanedioic acid and 3,6-dithiaoctanedioic acid.66 Mercaptobenzoic acids are used alone or with a cyclic imide solvent to produce lithographic... 

Babcock, G. T., El-Deeb, M. K., Sandusky, P. O., Whittaker, M. M., and Whittaker, J. W., 1992, Electron paramagnetic resonance and electron nuclear double resonance spectroscopies of the radical site in galactose oxidase and of thioether-substituted phenol model compounds, J. Am. Chem. Soc. 114 372793734. 

New types of acyclic nucleoside phosphonates (408-412) have been obtained using a multistep synthetic approach based on N-1, O- and S-alkylations of 4-and 2,4-substituted 6-hydroxy and 6-mercaptopyrimidines with diisopropyl 2-(chloroethoxy)methylphosphonate and (R) or (S) - [2-(diisopropylphos-phonyl)methoxy] propyl tosylate. Inhibitory activity against viruses of both the nucleoside phosphonates and the related phosphonic acids was investigated. It was found that the 6[2-(phosphonomethoxy)ethoxy]pyrimidines must bear an (unsubstituted) amino group concomitantly on both C-2 and C-4, or an amino on C-2 and an OH group on C-4, to display antiviral activity. Alkyl ethers are preferred over alkyl thioethers. The compounds of the 6-[2-(phos-phonomethoxy)ethoxy] and 6-[2-(phosphonomethoxy) propoxy]pyrimidine... 

Replacement or removal of the sulfonamide group at position 7 yields compounds with little or no diuretic activity. Saturation of the double bond to give a 3,4-dihydro derivative produces a diuretic that is 10-fold more active than the unsaturated derivative. Substitution with a lipophilic group at position 3 gives a marked increase in the diuretic potency. Haloalkyl, aralkyl, or thioether substitution increases the lipid solubility of the molecule and yields compounds with a longer duration of action. Alkyl substitution on the 2-N position also decreases the polarity and increases the duration of diuretic action. Although these compounds do have carbonic anhydrase activity, there is no correlation of this activity with their saluretic activity (excretion of sodium and chloride ions). 

Sterically hindered phenols, such as 2,6 di-tert-butyl-p-cresol (BHT), long chain 3-(3,5 di-tert-hutyl-4-hydroxyphenyl)-propionate or sebacate are the preferred substances for the stabilization of polystyrenes. Preferred thio compounds are long-chain thiodi-propionates. The combination of thio compounds with sterically hindered phenols leads to thioether substituted phenols. Suitable phosphorous compounds include substituted phenylphosphites, such as tris-nonylphenyl phosphite (TNPP) or phos-phonite. 

The preparation of substituted selenazole thioethers (Scheme 22) has already been described (35. 36). These compounds are obtained by the action of a haloketothioether on. for example, selenoacetamide. selenobenzamide, and A -ethylselenourea. These selenazoles have not been characterized, but they have been used as intermediates in the preparation of cyanine dyes. 

Halothiophenes, which are not activated through the presence of —I—M-substituents, undergo substitution smoothly under more forcing conditions with copper salts in pyridine or quinoline. Hence 3-cyanothiophene and 5-methyl-2-cyanothiophene have been obtained from the corresponding bromo compounds. 2-Bromothiophene reacts readily with aliphatic cuprous mercaptides in quinoline at 200°C to give thioethers in high yields. The use of the copper-catalyzed Williamson synthesis of alkoxythiophenes from iodo- or bromo-thiophenes and alcoholate has been mentioned before. The reaction of 2-bromothiophene with acetanilide in nitrobenzene in... 

Corrosion inhibition is primarily associated with acidizing. Buffered hydrofluoric acid compositions have been shown to be less corrosive (147). Corrosion inhibitors are designed to reduce the rate of reaction of fluid with metal surfaces, generally by forming films on the surfaces. Acetylenic alcohols and amines are frequently components of corrosion inhibitor blends. Other compounds that have been used include nitrogen heterocyclics, substituted thioureas, thiophenols, and alpha-aminoalkyl thioethers (148). 

As the final example in this section, a Li-mediated carboaddition/carbocycliza-tion process will be described. Thus, Cohen and coworkers observed a 5-e%o-trig-cy-clization by reaction of the lithium compound 2-349 and a-methyl styrene 2-350 to give 2-352 via 2-351 (Scheme 2.82). Quenching of 2-352 with methanol then led to the final product 2-353 [189]. In this process, 2-349 is obtained by a reductive lithia-tion of the corresponding phenyl thioether 2-348 with the radical anion lithium 1-(dimethylamino)naphthalenide (LDMAN) (2-354). Instead of the homoallylic substance 2-348, bishomoallylthioesters can also be used to provide substituted six-membered ring compounds. 

The readily available benzotriazolyl derivative of dimethyl sulfide, compound 821, can be alkylated on a-carbon in a stepwise manner to provide (a,a-disubstituted)alkyl thioethers 823 (Scheme 131). Hydrolysis of these thioethers under mild conditions (5% H2S04 at room temperature) furnishes ketones 824 in high yields. The anion derived from mono substituted (benzotriazol-l-yl)methyl thioether 822 adds to butyl acrylate to give intermediate 826 that can be hydrolyzed to y-ketoester 825. In another example of reactivity of a-(benzotriazol-l-yl)alkyl thioethers, treatment of thioether 822 with BunLi followed by phenyl isocyanate converts it into a-ketoanilide 828, via intermediate adduct 827 <1998JOC2110>. 

For comparison within the chalcogens, the oxidation potentials of the Ph-E-Me series 94, 95b, 96b, and 97b, where E = O, S, Se, Te, respectively, were evaluated by pulse radiolysis.Consistent with the analogous diaryl series, the values for this series indicate that the compounds are increasingly easy to oxidize, with telluride 97b most easily oxidized (0.74 V) and ether 94 least easily oxidized (1.62 V), with these values vs. NHE (Table 10). Eor a broader comparison, series of four or five para-substituted arylmethylsulfides, selenides, and tellurides, 95a-e, 96a-e, and 97a-d were prepared and their values determined in the same manner (Table 10). The same trends were observed, with the thioethers least... 

Interestingly, sulfonium ylides generated from electrophilic carbene complexes and sulfides can react with carbonyl compounds, imines, or acceptor-substituted alkenes to yield oxiranes [1320-1325], aziridines [1321,1326,1327] or cyclopropanes [1328,1329], respectively. In all these transformations the thioether used to form the sulfonium ylide is regenerated and so, catalytic amounts of thioether can be sufficient for complete conversion of a given carbene precursor into the... 

Compound 12 displays an altogether different reactivity pattern upon treatment with iodine in the presence of an ether or a thioether. Thus, the sole product of the reaction of 12 in THF with iodine was the anionic Mo complex [N(PPh3)2][2,2,2-(CO)3-2-I-7-0(CH2)4-c/oxo-2,1-MoCBioHio] (67), with the carborane cage having undergone a substitution at a boron vertex. The substitution occurs at a p boron atom in the CBBBB face that ligates the molybdenum atom. When 67 is treated with further iodine in THF no reaction occurs. However, treatment with iodine using... 

By prior substitution at the a-carbon centre (deprotonation, followed by sUylation), also asymmetrically functionalized bis(lithiomethyl)silanes like compound 161 are accessible from their substituted parent compounds (e.g. compound 160). This selective reaction sequence is based on the possibility of deprotonating bis(phenylthiomethyl)silane 155f with w-butyllithium without attacking the thioether groups (Scheme 58). ... 

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