Reactions of thiols

Published data on the reactivity of thiols, specifically C-, N-, P-, and S-sulfanylation reactions, halogenolysis of S-H bond, dealkylation, and oxidation, are reviewed.     

Reaction of aminothiazole-oximetosylates with thiols

The reaction of ethyl 2-(2-aminothiazol-4-yl)-2-tosyloxyiminoacetate and its tritylamino analogue with thiols gave ethyl 2-(5-R-thio-2-amino- or tritylamino-thiazol-4-yl)-2-oxoacetate derivatives. Structures were elucidated by ir, ¹H-, ¹³C-nmr and mass spectroscopy. A reaction mechanism is suggested.     

Heterocyclization reactions involving thiols

Information on the syntheses of sulfur-containing heterocycles involving thiols is systematized and generalized. Data on biological action of some among these systems are mentioned.     

Synthesis of thiols from isobornylphenols

4-(3-Sulfanylpropyl)-2-isobornyl-6-methylphenol and 4-(sulfanylmethyl)-2,6-diisobornylphenol were synthesized from the corresponding 4-(bromoalkyl)phenols according to known procedures. Isobornylphenol with a trimethylene linker was converted into thiol by alkaline hydrolysis of thiouronium salt. The methylene-bridged analog was obtained by reduction of S-benzyl thioacetate with LiAlH₄.     

Oxidation of thiols by sodium N-haloarylsulphonamides

The methods for direct titration of thiols with N-haloarylsulphonamides have been evaluated by studying the oxidation of 2-mercaptobenzoic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 2-naphthyl mercaptan, 2-mercaptoethanol, mercaptosuccinic acid, thiophenol, p-chlorothiophenol, butyl mercaptan and monothioglycerol, with chloramine-T (CAT), bromamine-T (BAT) and bromamine-B (BAB). The optimum conditions have been established. The precision was found to be poorer for titrations with CAT. BAB was found to give better precision and accuracy for the determination of all ten thiols studied, and is recommended for use.     

Enantioselective desymmetrization of meso-N-sulfonylaziridines with thiols

Desymmetrization of meso-N-sulfonylaziridines with thiols was realized using cinchonine-derived chiral quaternary ammonium salts as the catalyst. The corresponding chiral thio amines were provided in high yields (80–99%) and in good enantioselectivities (40–73% ee).     

Alternative chiral thiols for preparation of chiral CdS quantum dots covered immediately by achiral thiols

Developing of alternative chiral thiol stabilizers from the assembly of achiral thiol (e.g. thioglycolic acid) and chiral ligand (e.g. arginine) via both hydrogen bonding and electrostatic interactions was proposed and successfully applied to an efficient preparation of chiral CdS quantum dots (QDs). Chiral CdS QDs capped mainly with achiral thioglycolic acid were also obtained that may allow the chiral QDs to be modified for extended applications.     

Oxidation of thiols promoted by PhSeZnCl

The ability of PhSeZnCl 1 to catalyze the oxidation of thiols to disulfides has been evaluated and correlated to a catalytic GPx-like activity. The first evidence that vinyl phenylselenides can promote the oxidation of thiols reducing hydrogen peroxide through the formation of a selenoxide intermediate is also reported.     

Reaction of 5-azacinnoline with thiols

Previous conclusions regarding the reactions of 5-azacinnoline with mild bases at the C(₄) atom were confirmed: the corresponding 4-mercapto-5-azacinnoline derivatives are formed in the reaction of this compound with primary, secondary, and tertiary mercaptans and thiophenol under mild conditions. The effect of the temperature, basic catalysts, and oxidizing agents on the yields of the reaction products was studied. Assumptions regarding the mechanism of the process are expressed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1272–1276, September, 1978.     

Photochemical desulfurization of thiols and disulfides

A visible light-induced desulfurization process for thiols and disulfides using triethylphosphite and triethylborane is reported. The reaction can be effected on a range of organic molecules having either primary, secondary or tertiary thiol groups and disulfides without the need of protecting groups. Thus, after treating l-cystine 7, l-cystine dimethylester 8, thioctic amide 9 and glutathione disulfide 10, first with tributylphosphine, later with triethylborane/triethylphosphite under irradiation in a one-pot reaction, the corresponding desulfurized compounds l-Ala, l-Ala, 1-octanamide and γ-l-Glu-l-Ala-Gly, respectively, are prepared in high yields with retention of configuration.     

Additions of thiols to acetylenic sulfones

Thiol addition to acetylenic sulfones in the 1 - methylsulfonyl - 2 - arylethyne series has been investigated. In analogy with earlier reports on thiol additions to arylsulfonyl - 1 - alkynes no violations of the trans-addition rule have been observed. Besides the expected nucleophilic attack on the β-C-atom, considerable α-addition occurred.     

Phase-transfer catalysed ion-radical perfluoroalkylation of thiols

It has been shown that under conditions of phase-transfer catalysis under UV-irradiation perfluoroalkyl iodides react with aliphatic and aromatic thiols in the water-organic solvent media to form alkyl or aryl perfluoroalkyl sulfides in 60–80% yield.     

Reaction of α-alkoxyacroleins with thiols

Conclusions The nucleophilic or radical addition of thiols to -alkoxyacroleins leads to 2-alkoxy-3-organylthiopropanals. Depending on the reaction conditions, the product of the electrophilic reaction of the same reagents is a 2-alkoxy-2-organylthiopropanal or 1-alkoxy-1-organylthiopropanone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 722–724, March, 1986.     

Fluorous thiols in oligosaccharide synthesis

A new, almost odorless fluorous thiol is synthesized, which is utilized to prepare highly fluorinated thioglycosyl donors. These thioglycosides showed excellent reactivities in glycosylation reactions. The fluorous chain, stable under esterification, etherification, deacetylation, and glycosylation conditions, allowed facile purification of the thioglycosides by solid-phase extraction through fluorous silica gel. The fluorous thiol was readily recycled.     

Photodissociation of aromatic thiols and disulfides

For the first time, the quantum yields of cleavage of SS and SH bonds in a disulfide and a thiol and also the extinction coefficient of the photoinduced aminophenylthiyl radical were determined, on the basis of which the relation of the photodissociation quantum yield to the energy of an absorbed quantum was observed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 540–543, March, 1990.