Aromatic thiol

Various S-nucleophiles are allylated. Allylic acetates or carbonates react with thiols or trimethylsilyl sulfide (353) to give the allylic sulfide 354[222], Allyl sulfides are prepared by Pd-catalyzed allylic rearrangement of the dithio-carbonate 355 with elimination of COS under mild conditions. The benzyl alkyl sulfide 357 can be prepared from the dithiocarbonate 356 at 65 C[223,224], The allyl aryl sufide 359 is prepared by the reaction of an allylic carbonate with the aromatic thiol 358 by use of dppb under neutral condi-tions[225]. The O-allyl phosphoro- or phosphonothionate 360 undergoes the thiono thiolo allylic rearrangement (from 0-allyl to S -allyl rearrangement) to afford 361 and 362 at 130 C[226],... 

Arylidene-5-oxazolones undergo a ring-opening reaction with aromatic thiols and a second mole of thiol is then incorporated to give products such as 48. ... 

Molecular ion Aromatic thiols show intense molecular ions (see Figure 33.2). 

Thiols react more rapidly with nucleophilic radicals than with electrophilic radicals. They have very large Ctr with S and VAc, but near ideal transfer constants (C - 1.0) with acrylic monomers (Table 6.2). Aromatic thiols have higher C,r than aliphatic thiols but also give more retardation. This is a consequence of the poor reinitiation efficiency shown by the phenylthiyl radical. The substitution pattern of the alkanethiol appears to have only a small (<2-fokl) effect on the transfer constant. Studies on the reactions of small alkyl radicals with thiols indicate that the rate of the transfer reaction is accelerated in polar solvents and, in particular, water.5 Similar trends arc observed for transfer to 1 in S polymerization with Clr = 1.4 in benzene 3.6 in CUT and 6.1 in 5% aqueous CifiCN.1 In copolymerizations, the thiyl radicals react preferentially with electron-rich monomers (Section 3.4.3.2). 

Aliphatic or aromatic sulfmic acids are reduced by aliphatic or aromatic thiols in the presence of Me3SiCl (TCS) 14 to give disulfides [113]. Thus, tolylsulfinic... 

Kim, B., Beebe, J.M., Jun, Y, Zhu, X.Y. and Frisbie, C.D. (2006) Correlation between HOMO Alignment and Contact Resistance in Molecular Junctions Aromatic Thiols versus Aromatic Isocyanides. Journal of the American Chemical Society, 128, 4970—4971. 

By using 10 mol% of 51, MS4A, and t-BuSH, the desired product 52 was obtained in up to 98% ee in 80% yield. A complementary role by two metals (Ga and Li) in activating and positioning both of the substrates has been proposed. The MS4A (sodium aluminosilicate) accelerated the reaction however, the actual role of this additive was not clearly defined, although the possibilty that MS4A delivers Na ions was pointed out. Tomioka et al. reported the asymmetric Michael addition of an aromatic thiol to a,P-unsaturated esters in the presence of 8 mol% of 53 to provide 54 in up to 97% ee in 99% yield (Eq. 7.40) [47]. 

The most commonly employed routes for the preparation of the / -sulfatoethylsulfone group, which is the essential structural feature of vinylsulfone reactive dyes, are illustrated in Scheme 8.5. One method of synthesis involves, initially, the reduction of an aromatic sulfonyl chloride, for example with sodium sulfite, to the corresponding sulfinic acid. Subsequent condensation with either 2-chloroethanol or ethylene oxide gives the / -hydroxyethylsulfone, which is converted into its sulfate ester by treatment with concentrated sulfuric acid at 20 30 °C. An alternative route involves treatment of an aromatic thiol with 2-chloroethanol or ethylene oxide to give the /Miydroxyethylsulfonyl compound which may then be converted by oxidation into the /Miydroxyethylsulfone. 

Woodson LC, Ames MM, Selassie CD et al. Thiopurine methyltransferase. Aromatic thiol substrates and inhibition by benzoic acid derivatives. Mol Pharmacol 1983 24 471-478. 

In 1978 and 1980 the coupling of aryl bromides and iodides with both aliphatic and aromatic thiols was first reported in the presence of NaO-t-Bu and Pd(PPh3)4 (Equation (35)).118,119 In contrast to aryl halide aminations and etherifications, the thiation reactions did not require unusual catalysts. Yet, reactions that form aryl alkyl sulfides from alkyl thiols occurred in modest yields in many cases ... 

The halogen in 5-bromofuran-2-carboxaldehyde is readily displaced by aromatic thiols, and the aromatic residue can be provided by pyridazine, benzeneselenazole, benzimidazole, benzoxazole, etc. as well as benzene.181... 

Kim B, Beebe JM, Jun Y, Zhu XY, Frisbie CD (2006) Correlation between HOMO alignment and contact resistance in molecular junctions aromatic thiols versus aromatic isocyanides. J Am Chem Soc 128 4970 1971... 

Pinney et al. reported the synthesis of benzothiophene CA4 analogs and an example synthesis is given in Scheme 38 [83]. Benzothiophene (145) was produced by reacting aromatic thiol 146 with a-bromoacetophenone 147 to generate the sulfide 148. Compound 148 was then cyclized to the benzothiophene 149 using polyphosphoric acid and heat. Formation of 145 was achieved by Friedel-Crafts aroylation of 149 with the methoxybenzoyl chloride 144. 

There have been fewer studies of the reactions of M ions with potential ligand molecules. Laser ablation, which has been the major ionization source for the production of bare metal ions, produces very few negative ions. Electron impact with low-energy electrons (12 eV) of metal carbonyls has been used to produce [Co(CO)4]- and Fc( CO)4 from Co2(CO)8 and Fe(CO)5. Collision-induced dissociation of these two anions produced Co- and Fc, which could be isolated. Both Co- and Fe were reacted with H2S, aliphatic thiols, aromatic thiols, CS2, and disulfides (153). Reactions with H2S gave the metal monosulfide anion [MS]-, which reacted with H2S by two pathways. 

Under aprotic conditions, prototropic transformations of thiols are relatively slow, so one can observe distinct waves of the oxidation of the protonated form and of its parent base [19, 20]. Normally, the oxidation of thiols (aliphatic, aromatic, and heteroaromatic) affords diorganyl-disulfides. So various aliphatic and aromatic thiols are easily converted into the corresponding disulfides upon oxidation in MeOH/MeONa with the yields ranging... 

The possibilities afforded by SAM-controlled electrochemical metal deposition were already demonstrated some time ago by Sondag-Huethorst et al. [36] who used patterned SAMs as templates to deposit metal structures with line widths below 100 nm. While this initial work illustrated the potential of SAM-controlled deposition on the nanometer scale further activities towards technological exploitation have been surprisingly moderate and mostly concerned with basic studies on metal deposition on uniform, alkane thiol-based SAMs [37-40] that have been extended in more recent years to aromatic thiols [41-43]. A major reason for the slow development of this area is that electrochemical metal deposition with, in principle, the advantage of better control via the electrochemical potential compared to none-lectrochemical methods such as electroless metal deposition or evaporation, is quite critical in conjunction with SAMs. Relying on their ability to act as barriers for charge transfer and particle diffusion, the minimization of defects in and control of the structural quality of SAMs are key to their performance and set the limits for their nanotechnological applications. 

Similar to other fundamental studies on SAMs, alkane thiols on Au(l 11) have also been prevailing in electrochemistry with, however, aromatic thiols receiving increased attention. A major topic has been formation and stability of SAMs and... 

Several groups investigated aromatic thiol systems for the formation of rigid, conjugated SAM systems [86-94] and it soon became clear that among the discussed systems, mercaptobiphenyls and 4 -substituted-4-mercaptobiphenyls are promising candidates and currently the most intensively studied thiol-based SAM systems. 

The reaction of [TcOCU] with various monodentate aromatic thiols in methanol produces complexes of the general formula [TcO(SAr)4] (89), which can be precipitated with bulky cations. The X-ray crystal structure of the complex with Ar = mesityl has been elucidated and has square-pyramidal geometry, with the Tc atom displaced from the basal plane by about 0.846 Direct... 

Fairchild EJ, Stokinger HE Toxicologic studies on organic sulfur compounds. 1. Acute toxicity of some aliphatic and aromatic thiols (mercaptans). Am Ind Elyg Assoc J 19 171-189, 1958... 

---