Gonzalez-Fernandez, Rebeca published the artcileCatalytic hydration of cyanamides with phosphinous acid-based ruthenium(
The synthesis of a large variety of ureas (26 examples) was successfully accomplished by hydration of the corresponding cyanamides using the phosphinous acid-based complexes I [M = Ru, Os] as catalysts. The reactions proceeded cleanly under mild conditions (40-70°), in the absence of any additive, employing low metal loadings (1 mol%) and water as the sole solvent. In almost all the cases, the osmium complex I [M = Os] featured a superior reactivity in comparison to that of its ruthenium counterpart I [M = Ru]. 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 C≡N bond depopulates electronically the nitrile carbon by inductive effect when coordinated to the metal center, thus favoring the intramol. 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 exptl. evidence of the generation of the metallacyclic intermediates was obtained by studying the reactivity of I [M = Ru] towards dimethylcyanamide in methanol and ethanol. The reactions afforded compounds II·SbF6 [R = Me, Et], resulting from the alcoholysis of the metallacycle, which could be characterized by single-crystal X-ray diffraction.
Catalysis Science & Technology published new progress about 2451-91-4. 2451-91-4 belongs to amides-buliding-blocks, auxiliary class Nitrile,Amine,Benzene, name is N,N-Dibenzylcyanamide, and the molecular formula is C15H14N2, SDS of cas: 2451-91-4.
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