625372-58-9Relevant academic research and scientific papers
Facile Ni(II)/Ketoxime-Mediated Conversion of Organonitriles into Imidoylamidine Ligands. Synthesis of Imidoylamidines and Acetyl Amides
Kopylovich, Maximilian N.,Pombeiro, Armando J. L.,Fischer, Andreas,Kloo, Lars,Kukushkin, Vadim Yu.
, p. 7239 - 7248 (2003)
Treatment of alkyl nitriles with NiX2·6H2O (X = Cl, NO3) and 2-propanone oxime, followed by (X = Cl) addition of [i-Pr4N](NO3) for precipitation of the product, resulted in the formation of amidinium nitrates [RC(=NH2)NH 2]-(NO3) (R = Me, Et, n-Pr). The reaction went to another direction with NiX2·2H2O, i.e., the reaction between neat RCN (R = Me, Et, n-Pr, i-Pr, n-Bu, CH2Cl, CH 2C6H4OMe-p) and NiCl2·2H 2O/2-propanone oxime (other ketoximes can also be used) gave the (imidoylamidine)Ni(II) complexes [Ni{N(H)=C(R)NHC(R=NH}2] 2+ (12+-72+). The latter were isolated in good yields (65-91%) as the bis-chloride salts 1·Cl2-6· Cl2 and the mixed salt 7·(Cl)(p-MeOC6H 4-CH2CO2). Remarkably, the latter transformation does not proceed at all if NiCl2·2H 2O or the ketoxime are taken alone. Liberation of imidoylamidines was performed for one alkyl-containing complex [2·Cl2] and one benzyl-containing complex [7·(Cl)(p-MeOC6H 4CH2CO2)], by (i) addition of HBF 4·Et2O to the acetonitrile solution of the complexes to yield [N(H)=C(R)NHC(R)=NH]·2HBF4 (R = Et 8 and R = CH2C6H4OMe-p 9) or (ii) substitution for ethanediamine (en) with following precipitation of the complex [Ni(en) 3]Cl2 with formation of free N(H)=C(R)NHC(R)=NH (R = Et 10 and R = CH2C6H4OMe-p 11). In contrast to the liberation in nonaqueous media, treatment of 2·Cl2 and 7· (Cl)(p-MeOC6H4CH2CO2)with Na2EDTA·2H2O in water-methanol solutions led to substitution and hydrolysis to furnish the acyl amides {EtC(=O)}2NH (12) and {p-MeOC6H4CH2C(=O)}2NH (13). Alternatively, 12 and 13 were obtained by hydrolysis of 10 and 11 in water at pH ca. 8.5. It was shown that the oxime complexes trans-[NiCl 2-(C4H8C=NOH)4] (14) or cis-[Ni(O,O-NO3)2(C4H8C=NOH) 2] (15) can be intermediates in the formation of amidines and imidoylamidines. The sequence of the Ni(II)/oxime mediated formation of (imidoylamidine)Ni complexes and liberation (or hydrolytic liberation) of the ligands opens up a novel, facile and environmentally benign route to imidoylamidines and acyl amides.
