3- -pyridinethione

Oxidation of a pyridinethione gives the corresponding sulfonic acid, eg, 6-carboxy-2-pyridinesulfonic acid [18616-02-9] from 6-carboxy-2-pyridinethione [14716-87-1] (eq. 14) (41). 

A stereoselective radical reaction of the ester of M-hydroxy-2-pyridinethione (see also Sect. 4.1) to chiral vinylphosphine oxides has also been described and moderate to good diastereomeric ratios have been obtained for the compound 112 [70] (Scheme 33). 

The synthesis of chloromethylthio heterocycles, e.g., 127 had been described by Goralski and Burk193 in the reaction of benzothiazole-2-thiones, 2-pyridinethiones, and 2-quinolinethiones with chlorobromomethane. In the case of l,3,4-thiadiazole-2,5-dithione, the reaction was made with the preformed alkali metal salt. 

KGS84). /3-Cyanoenamines interact with malonodinitrile followed by a reaction with phenyl isothiocyanate leading to 2-pyridone and 2-pyridinethione derivatives (95H2195) (Scheme 19). 

Thioethers have also been prepared on cross-linked polystyrene by radical addition of thiols to support-bound alkenes and by reaction of support-bound carbon radicals (generated by addition of carbon radicals to resin-bound acrylates) with esters of l-hydroxy-l,2-dihydro-2-pyridinethione ( Barton esters Entry 6, Table 8.5). Additional methods include the reaction of metallated supports with symmetric disulfides (Entries 7-9, Table 8.5) and the alkylation of polystyrene-bound, a-lithiated thioani-sole [65],... 

Pyrithione (zinc salt of) is used as a component of antidandruff shampoos and as a bactericide in soap and detergent formulations. This compound (2-mercaptopyridine N-oxide) exists in equilibrium with N-hydroxy-2-pyridinethione and is a fungicide and bactericide, prepared by reaction of 2-chloropyridine N-oxide with sodium hydrosulfide and sodium sulfide. This compound is also known as Omadine, Its formula is shown below. 

The tautomerism between 2-pyridinethione and 2-pyridine thiol has also been examined using variable temperature IR spectroscopy <2002JOC9061>. No evidence for the S-H stretch was observed in a range of solvents and this was determined computationally to be a solvent effect the thiol form is more stable in the gas phase but the thione is more stable in solution. (The effect of phase on the tautomers of 2-hydroxy, 2-amino-, and 2-thiopyridine has also been studied by infrared spectroscopy <2001SAA2659>.) Dimerization is also observed, with the indication that the thione dimer predominates, in contrast with the computational studies described above. 

Pyridinethiol is in equilibrium with 2-pyridinethione and it is been previously thought that the thiol is more stable in nonpolar solvents while the thione is more stable in polar solvents. Recent variable temperature Fourier transform IR experiments and computational studies calculated at the B3LYP/6-311 level of theory indicate that the thione is more thermodynamically stable than the thiol in nonpolar solvents and that tautomerism occurs via the dimer <2002JOC9061> (Equation 82). 

Alkyl halides give alkylthiopyridines or -azines, e.g., 880 882, or in the absence of an NH group, alkylthio pyridinium rings. 2-Pyridinethiones undergo palladium(0)-catalyzed enantioselective S-allylation with cyclic and acyclic allylcarbo-nates to give allylic sulfides, for example, 885, with moderate enantiomeric selectivity (Scheme 97) <2003CEJ4202>. 

Reaction of tertiary enaminones with benzoyl isothiocyanate gives substituted 2-pyridinethiones in moderate yields, indicating the reactivity of enaminones at a-methyl group6 (equation 2). Phenylisothiocyanate reacts simply at the -position7 (equation 3). 

HYDROXY-2-PYRIDINETHIONE), SODIUM SALT, TECH see MCQ750... 

Related to the reaction of thiols are pyridine thiones since they exist in an apparent tautomeric equilibrium shown in Equation 10.59 for the 2-pyridinethione/2-pyridi-nethiol system. 

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