Oxidative desulfurization of disubstituted thioureas using Pb(II) salts and investigation of pKa-dependent regioselective N-acylation
摘要:
A highly efficient method for the N-acylation of both symmetrical and unsymmetrical thioureas by the use of lead (II) salts and triethylamine has been achieved. The reaction gives regioselective N-acylated product for unsymmetrical thiourea. For unsymmetrical thiuourea, regioselective N-acylation takes place towards the amine having lower pKa. A linear correlation between the pKas of the amines and the regioselective N-acylation is found. Another attractive feature of this transformation is that lead sulfide, which is important to material science, is obtained as a side product (nanocubes of 20nm).
Über die Reaktion von Quadratsäure mit Carbodiimiden
作者:Johann Grünefeld、Gerwalt Zinner
DOI:10.1002/ardp.19853181203
日期:——
Aus Quadratsäure (5) und Carbodiimiden 2 wurden erhalten: N‐(2‐Hydroxy‐3,4‐dioxo‐1‐cyclobutenyl)‐N,N′‐dialkylharnstoffe 6 bzw. N,N′‐Diaryl‐quadratsäurediamide 8, mit N‐Isopropyl‐N'‐phenylcarbodiimid (2f) in Abhangigkeit von den Reaktionsbedingungen N‐(2‐Hydroxy‐3,4‐dioxo‐1‐cyclobutenyl)‐N'‐isopropyl‐N‐phenylharnstoff (17) bzw. 3,4‐Di(3‐isopropyl‐1‐phenylureido)‐3‐cyclobuten‐1,2‐dion (19).
方酸 (5) 和碳二亚胺 2 得到:N-(2-羟基-3,4-二氧代-1-环丁烯基)-N, N'-二烷基脲 6 和 N, N'-二芳基-方酸二酰胺 8,其中 N -异丙基-N'-苯基碳二亚胺(2f)取决于反应条件N-(2-羟基-3,4-二氧-1-环丁烯基)-N'-异丙基-N-苯基脲(17)或3,4-二(3-异丙基-1-苯基脲基)-3-环丁烯-1,2-二酮(19)。
Carbodiimides as important intermediates in the reaction of isocyanates with carboxylic acids
作者:A. H. M. Schotman、W. J. Mijs
DOI:10.1002/recl.19921110205
日期:——
The reaction between isocyanates and carboxylic acids is known to lead to amides. We have studied the mechanism of catalysis of this reaction by phospholene oxides.