622-51-5Relevant articles and documents
Reaction of N-arylcarbamoyl-1,4-benzoquinone imines with sodium arenesulfinates
Konovalova,Avdeenko,Sergeeva,Menafova
, (2014)
N-Arylcarbamoyl-1,4-benzoquinone imines possessing at least one free ortho position with respect to the carbonyl carbon atom in the quinoid ring react with sodium arenesulfinates according to the nucleophilic 1,4-addition pattern with complete regioselect
Green and efficient synthesis of thioureas, ureas, primary: O -thiocarbamates, and carbamates in deep eutectic solvent/catalyst systems using thiourea and urea
Bagherzadeh, Nastaran,Sardarian, Ali Reza,Inaloo, Iman Dindarloo
supporting information, p. 11852 - 11858 (2021/07/12)
An efficient and general catalysis process was developed for the direct preparation of various primary O-thiocarbamates/carbamates as well as monosubstituted thioureas/ureas by using thiourea/urea as biocompatible thiocarbonyl (carbonyl) sources. This procedure used choline chloride/tin(ii) chloride [ChCl][SnCl2]2 with a dual role as a green catalyst and reaction medium to afford the desired products in moderate to excellent yields. Moreover, the DES can be easily recovered and reused for seven cycles with no significant loss in its activity. Besides, the method shows very good performance for synthesizing the desired products on a large scale.
Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights
álvarez, Daniel,Cadierno, Victorio,Crochet, Pascale,González-Fernández, Rebeca,López, Ramón,Menéndez, M. Isabel
, p. 4084 - 4098 (2020/07/09)
The synthesis of a large variety of ureas R1R2NC(O)NH2 (R1 and R2 = alkyl, aryl or H; 26 examples) was successfully accomplished by hydration of the corresponding cyanamides R1R2NCN using the phosphinous acid-based complexes [MCl2(η6-p-cymene)(PMe2OH)] (M = Ru (1), Os (2)) as catalysts. The reactions proceeded cleanly under mild conditions (40-70 °C), in the absence of any additive, employing low metal loadings (1 molpercent) and water as the sole solvent. In almost all the cases, the osmium complex 2 featured a superior reactivity in comparison to that of its ruthenium counterpart 1. In addition, for both catalysts, the reaction rates observed for the hydration of the cyanamide substrates were remarkably faster than those involving classical aliphatic and aromatic nitriles. Computational studies allowed us to rationalize all these trends. Thus, the calculations indicated that the presence of a nitrogen atom directly linked to the CN bond depopulates electronically the nitrile carbon by inductive effect when coordinated to the metal center, thus favouring the intramolecular nucleophilic attack of the OH group of the phosphinous acid ligand to this carbon. On the other hand, the higher reactivity of Os vs. Ru seems to be related with the lower ring strain on the incipient metallacycle that starts to form in the transition state associated with this key step in the catalytic cycle. Indirect experimental evidence of the generation of the metallacyclic intermediates was obtained by studying the reactivity of [RuCl2(η6-p-cymene)(PMe2OH)] (1) towards dimethylcyanamide in methanol and ethanol. The reactions afforded compounds [RuCl(η6-p-cymene)(PMe2OR)(NCNMe2)][SbF6] (R = Me (5a), Et (5b)), resulting from the alcoholysis of the metallacycle, which could be characterized by single-crystal X-ray diffraction. This journal is
