3- -pyridinethione synthesis

Pyridinethiones acylation, 2, 357 alkylation, 2, 357 aromaticity, 2, 148 protonation, 2, 357 tautomerism, 2, 356 Pyridine-2-thiones aromaticity, 2, 156 basicity, 2, 157 oxidation, 2, 357 N-oxide, sodium salt biocide, 1, 399 synthesis, 2, 360... 

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. 

Regioselective synthesis of substituted 3-cyano-2(lT/)-pyridinethiones and -selenones from unsymmetrical p-enaminoketones 90MI5. 

Synthesis of (257) including the tricyclic derivatives, involves a cyclocondensation reaction of l-amino-2-pyridinethiones with a-bromocarbonyl compounds at reflux temperature in benzene or ethanol (Equation (55)) <828645,88H(27)733>. 

Sulfur heterocycles. Some papers report on the synthesis of thiopyrans from cyanothio-acetamides and various ylidenemalononitriles. Subsequent rearrangement yielded pyridinethiones. So arylidenemalononitriles (179) yielded 225 in cold ethanol with catalysis of triethyl amine. Refluxing 225 in ethanol/triethylamine gave 226. ... 

Macrolactonization. When a carboxylic acid is treated with 2,2 -dipyridyl disulfide in the presence of Triphenylphosphine, the corresponding 2-pyridinethiol ester is formed. Corey and Nicolaou have developed an efficient method for the synthesis of macrocyclic lactones based on these 2-pyridinethiol esters. When an m-hydroxy thiolester is heated in refluxing xylene under high dilution conditions (10 M, typically accomplished with syringe pump techniques), macrolactonization occurs, liberating triphenylphosphine oxide and pyridinethione. The reaction is quite general and is believed to proceed by a double activation mechanism in which the basic 2-pyridinethiol ester simultaneously activates both the hydroxy and the carboxylic acid moieties with a single proton transfer. It has been shown that the cyclization rate is not affected by the presence of acids, bases, or any of the possible reaction contaminants. ... 

Alkene Formation. The elimination of pyridinethione or 2-pyridylsulfenic acid forms the basis of a number of alkene syntheses. For example, treatment of dithioacetal anions with 2,2 -dipyridyl disulfide affords the a-thiopyridyl derivative, which undergoes elimination at below room temperature to give ketene dithioacetals. Ester enolates have been similarly treated, although m-Chloroperbenzoic Acid is first used to generate the sulfoxide which reacts further to yield an a,p-unsaturated ester. This methodology has been applied to the synthesis of methyl dehydrojasmonate (7) (eq 7). ... 

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