Thioamide derivatives react with superoxide radical anion ($O^{\bar{\cdot}}_2$) to convert to the corresponding amides. When the reaction of thioamides with potassium superoxide was carried out in anhydrous dimethyl sulfoxide(DMSO), desulfurization of thioamides was slow even at 70℃. However, in contrast to the desulfurization in DMSO, the same reaction in THF or acetonitrile afforded the corresponding amides in good yields under the mild condition. The desulfurization appears to be initiated via the formation of peroxysulfur intermediate.
While, N,N'-dibenzyldithiooxamide reacted with potassium superoxide to give N,N'-dibenzoyldithiooxamide as a major product, together with small amount of N,N'-dibenzylthiodioxamide.
Thiosulfinates have been usually known to be unstable, and easily to be decomposed to the corresponding disulfide and thiosulfonate. In the course of studying 2,2'-dithiobisphenol, it was found that the disulfide was readily oxidized with m-chloroperbenzoic acid(MCPBA) to form stable 2,2-dihydroxy-diphenylthiosulfinate. The reason why thiosulfinate is so unusually stable is probably due to its intramolecular hydrogen bond between the hydrogen of hydroxyl groups and the oxygen of sulfinyl group. Further oxidation of thiosulfinate with MCPBA afforded the corresponding disulfide and thiosulfonate which may be produced via the formation of unstable α-disulfoxide.
생체내의 탈황반응에 대한 대사작용을 설명하기 위한 모델반응으로써, 티오아미드 유도체를 칼륨 슈퍼옥사이드와 여러가지 유기용매하에서 반응시켜 보았다.
티오 아미드와 슈퍼옥사이드를 실온에서 디메틸 설폭사이드, 아세토니트릴, 테트라 히드로 폭란과 같은 유기 용매하에서 반응시켜본 결과 탈황반응이 일어났다. 디메틸설폭사이드 용매하에서는 테트라 히드로 퓨란, 아세토 니트릴같은 용매에서 보다 탈황 반응이 매우 천천히 진행되었다. 티오 아미드의 탈황반응은 퍼옥시 술퍼네이트 중간체를 거쳐서 일어난다고 예상된다.
반면에, N,N'-디벤질디티오옥사이드는 슈퍼옥사이드와 반응하여 주된 생성물로서 N,N'-디벤조일디티오옥사이드를 얻을수 있었다.
안정한 티오술피네이트의 합성과 특성조사
일반적으로 티오술피네이트는 불안정하므로 쉽게 깨져서 디설피드와 티오술포네이트로 변한다고 알려져 있다.
