Thiol resin

This synthesis demonstrated that the neighboring-group participation effect on the stereoselectivity of glycosylation reactions can be extended to sohd-phase processes. In this case, milder and more practical cleavage conditions than previously discussed were established. The use of /V- bromosuccinimide as the thiophilic reagent in acetone/water or tetrahydrofuran/methanol permitted the release of oligosaccharides in form of lactols or 1-0-Me glycosides, respectively. The tetrasaccharide derivative was isolated in 34% yield from thiol resin 3 (80% yield per step). 

Thiols can be linked to insoluble supports as disulfides by disulfide interchange. Mixed disulfides can be prepared on insoluble supports by treating support-bound thiols with excess activated disulfide (e.g. 2-benzothiazolyl, 2-nitrophenyl, 3-nitro-2-pyridyl disulfides [60,676] or a methanethiosulfonate MeS02-SR [677] Figure 3.33), or by treating a support-bound disulfide (e.g. a 2-pyridyl disulfide [191]) with a thiol. Resin-bound disulfides are stable under the conditions of standard Fmoc peptide synthesis, but can be cleaved by reducing agents (Entries 8 and 9, Table 3.37 [191,676,678-681]). 

De Clercq [38] has utilized a sulfide linker, cleaved by a radical process initiated by electron transfer, in a solid-phase Julia-type olefination process. Alkylation of an aryl thiol resin followed by mCPBA oxidation gave supported sulfone 217 (Scheme 54). Successive treatment of the resin with n-butylhthium and an aldehyde followed by trapping of the resultant alkoxide with benzoyl chloride gave resin-bound a-benzoyloxy sulfone 218. Olefins 219 and 220 were released from the sohd support upon reduction with a single-electron-transfer reagent and elimination of the sulfone link-... 

Chelating agents for mercury, such as cysteine and penicillamine, have been used as intervention measures to reduce the concentration of inorganic mercury. However, chelation therapy has yielded variable success in cases of alkyl mercury poisoning. Studies of MMM suggest that chelators may reduce brain and blood mercury levels if started within a few days after exposure. Surgical gallbladder drains and oral administration of a nonabsorbable thiol resin have been applied in order to interrupt biliary excretion and reabsorption of mercury by the intestine. 

There is no known useful treatment for methylmercury poisoning. A variety of chelating agents, such as D-penicillamine, l-acetyl-D,L-penicillamine, thiol resins, activated charcoal, BAL (British Antilewisite 2,3-dimercaptopropanol), and meso-2,3-dime-rcaptosuccinic acid, have been used to treat methyl-mercury exposure but with limited to no success. 

In addition to the silica or polymer based resins mentioned above, polymer based resins with specific chemistries at the functional group have also been widely used as palladium scavengers for synthetic organic reactions. These include macroporous polystyrene-bound trimercaptotriazine (TMT). It, along with the thiol resin, has been found to be highly effective in reducing the concentration of palladium in both aqueous and non-aqueous solutions [18]. 

Methylmercury compounds undergo extensive enterohepatic recirculation therefore, introduction of a nonabsorbable mercury-binding substance into the intestinal tract should facilitate their removal from the body. A polythiol resin has been used for this purpose in humans and appears to be effective. The resin has certain advantages over penicillamine. It does not cause redistribution of mercury in the body with a subsequent increase in the concentration of mercury in blood, and it has fewer adverse effects than do sulfhydryl agents that are absorbed. Clinical experience with various treatments for methylmercury poisoning in Iraq indicates that penicillamine, N-acetylpenicillamine, and an oral nonabsorbable thiol resin all can reduce blood concentrations of mercury however, clinical improvement was not clearly related to reduction of the body burden of methylmercury. 

Thus, complicated metal organic compounds are synthesized by the ene-thiol reaction. The ene-thiol reaction can be applied to polymer resins for UV nanoimprints. The ene-thiol resin for UV nanoimprints is reported by Ffagberg et al. and shown in Figure 4.18. Ene-thiol resin is optically cured by step reactions between a compound (ene) with two or more double bonds in the molecule and another compound with two or more thiols in the molecule. The... 

The thiol resins —SH and 0—CH2SH have also been used in Michael additions in the presence of tetrabutyl ammonium hydroxide and a source of protons. A large number of Michael acceptors were used successfully and gave the adducts in essentially quantitative yields Scheme 10 shows two reactions involving methyl acrylate and cyclohexen-2-one. Practical applications of this reaction to the extraction of unsaturated lactones from solutions have been investigated (Ref. 61, 62). 

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