ABATRACT 已经开发了一种从异硫氰酸酯在水中的自缩合反应直接得到N , N '-二取代脲/硫脲的方法。这种访问容忍了芳环上的多种官能团,为N , N '-二取代脲/硫脲提供了一种实用且环境友好的工艺,从安全且易于获得的起始材料以中等至优异的产率。还提出了尿素脱硫自缩合反应的合理机理,并借助中间体研究的 ESI 质谱分析证明了二叔丁基过氧化物 (DTBP) 和铜催化剂在本策略中的作用。
Thirty symmetrical diaryl urea derivatives were synthesised in moderate to excellent yields from arylamine and triphosgene with triethylamine as a reducing agent for the intermediate, isocyanate. It was significant that part of the products could be collected in almost quantitative yield without column chromatography. The procedure under mild reaction conditions was tolerant of a wide range of functional
Preparation of Isocyanates from Primary Amines and Carbon Dioxide Using Mitsunobu Chemistry<sup>1</sup>
作者:Dilek Saylik、Michael J. Horvath、Patricia S. Elmes、W. Roy Jackson、Craig G. Lovel、Keith Moody
DOI:10.1021/jo982362j
日期:1999.5.1
Primary alkylamines 1 and hindered arylamines 1 give high yields of isocyanates 5 when reacted with carbon dioxide and the Mitsunobu zwitterions 4 generated from dialkyl azodicarboxylates and Bu3P in dichloromethane at -78 degrees C. Use of Ph3P still gave high yields of isocyanates from reactions of primary alkylamines, but only low yields were obtained from reactions of aromatic amines. Reactions which failed to give high yields of isocyanates gave either carbamoylhydrazines 6 and/or dicarbamoylhydrazines 10 and/or triazolinones 7. The triazolinones were shown to arise from reactions of reactive aryl isocyanates with the Mitsunobu zwitterion. The carbamoylhydrazines were shown not to arise from reaction, of isocyanate with reduced dialkyl azodicarboxylates, and a mechanism for their formation is proposed. Single-crystal X-ray analyses confirmed the structures of 6, 7, and 10.
Wchman, Petra; Borst, Leo; Kamer, Paul C. J., Chemische Berichte, 1997, vol. 130, # 1, p. 13 - 21
作者:Wchman, Petra、Borst, Leo、Kamer, Paul C. J.、Van Leeuwen, Piet W. N. M.
DOI:——
日期:——
Di-tert-butyl peroxide (DTBP)-mediated synthesis of symmetrical <i>N</i>,<i>N</i>′-disubstituted urea/thiourea motifs from isothiocyanates in water
ABATRACT A direct approach to N,N′-disubstituted urea/thiourea from the self-condensation reactions of isothiocyanates in water has been developed. This access tolerated a wide range of functional groups on the aromatic ring, providing a practical and environment-friendly process to N,N′-disubstituted urea/thiourea in moderate to excellent yields from safe and easily available starting materials. A
ABATRACT 已经开发了一种从异硫氰酸酯在水中的自缩合反应直接得到N , N '-二取代脲/硫脲的方法。这种访问容忍了芳环上的多种官能团,为N , N '-二取代脲/硫脲提供了一种实用且环境友好的工艺,从安全且易于获得的起始材料以中等至优异的产率。还提出了尿素脱硫自缩合反应的合理机理,并借助中间体研究的 ESI 质谱分析证明了二叔丁基过氧化物 (DTBP) 和铜催化剂在本策略中的作用。
Conformation and stereodynamics of 2,2′-disubstituted N,N′-diaryl ureas
作者:Jonathan Clayden、Loïc Lemiègre、Mark Pickworth、Lyn Jones
DOI:10.1039/b802673d
日期:——
Except in the most hindered of cases, N,N'-diaryl N,N'-dimethyl ureas adopt a conformation with the two aryl rings disposed cis to one another. Variable temperature NMR studies reveal the rate at which the Ar-N bonds rotate as well as the conformational preference of ortho disubstituted ureas in which more than one cis orientation is possible. In general, a conformation in which the aryl rings lie