Carbon-nitrogen bond fission in ureas and thioureas. Preparation of alkyl and aryl isothiocyanates using carbon disulfide and butyllithinm or a Grignard reagent.
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概要
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The carbon-nitrogen bond in <I>N</I>,<I>N</I>′-diaryl- and dialkyl-thioureas or -ureas was easily cleaved by the metallation of thioureas or ureas using butyllithium, followed by the addition of an excess of carbon disulfide or 1,3-dithiolan-2-thione in tetrahydrofuran under reflux, to afford about two mol of the corresponding isothiocyanates per mol of the thioureas or ureas used. Instead of butyllithium, ethylmagnesium bromide was also effective in such a type of carbon-nitrogen bond fission of the (thio) ureas in refluxing tetrahydrofuran, and in this case the addition of carbon disulfide was not required. To explain these results, a six-centered decomposition of the dilithium salt of <I>N</I>-dithiocarboxy(thio) urea in the reaction using butyllithium was tentatively proposed, while a four-centered mechanism seems applicable to the reaction using ethylmagnesium bromide.
- 公益社団法人 日本化学会の論文
著者
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Aizawa Toshiyuki
Department Of Gastroenterology Jichi Medical School
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Fujinami Tatsuo
Department of Material Science and Chemical Engineering, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561, Japan
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Sakai Shizuyoshi
Department of Applied Chemistry, Faculty of Engineering, Shizuoka University
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