[2044-27-1] · C6H7NS · 1-Methyl-2(1H)-pyridinethione · (MW 125.21)
(sulfur transfer; carbonyl activation)
Physical Data: pale yellow leaflets; mp 89-90 °C.
Preparative Method: prepared in 80-90% yield from commercially available 1-methyl-2(1H)-pyridone by treatment with Phosphorus(III) Iodide at 130 °C for 4-5 h.
The reactivity of 1-alkyl-2(1H)-pyridone (and -pyridinethione) derivatives has been studied extensively by Tomisawa.3
The title reagent (1) reacts with acyl chlorides to produce 2-acylthio-1-methylpyridinium salts (2) as stable hygroscopic solids (eq 1). These may then be treated with a variety of oxygen and nitrogen nucleophiles in the presence of base to effect transfer of the acyl group to the nucleophilic species to produce (3) and regenerate (1).4
The reagent has been used as a method of producing thiols from halides by alkylation on sulfur followed by hydrolysis.5 The initial alkylation proceeds best with activated halides such as benzylic halides or a-halo carbonyl compounds, although the conversion of bromocyclohexane to the corresponding thiol occurs in 70% yield. An example (eq 2) shows the compatibility and mildness of the reagent.6 No b-elimination product was reported.
Kim F. Albizati
University of California, San Diego, CA, USA