81756-70-9Relevant academic research and scientific papers
Fac-Specific syntheses of homochiral [Fe(NN′)3] 2+ complexes (NN′ = pyridine keto-hydrazone); Origins of the stereoselectivity
Sebli, Cynthia Paul,Howson, Suzanne E.,Clarkson, Guy J.,Scott, Peter
, p. 4447 - 4454 (2010)
The 2-pyridinehydrazones (from condensation of pyridine-2-carbaldehyde and hydrazines) have previously been noted to have poor ligating ability as a result of a sterically demanding planar conformation. Destabilisation of this conformation is achieved through simple use of the ketohydrazones, and as a result the diamagnetic chiral tris-bidentate diimine complexes fac-[FeL 3]2+ are readily isolated. In the solid state, inter-ligand π-π stacking and complex/counter-ion H-bonding are apparent, and these features persist in solution according to dynamic NMR spectra, which also indicate extremely high stereoselectivity for the fac isomers (>200:1). The compounds crystallise as conglomerates, and time-resolved CD spectra of non-racemic samples indicate a high degree of persistence of chirality (racemisation t1/2ca 77 min). Variations of solvent and counter-ion indicate that H-bonding is unimportant in determining the structure of the cation. The fac-selectivity arises in the induction of a chiral conformation in the coordinated ligand, and the fact that such non-planar ligands can only be accommodated about the Fe(ii) centre if they all have the same absolute configuration. Adding a hydrazine N-methyl group increases the steric demand further, while retaining the novel non-planar conformation, and as a result paramagnetic chiral bis-bidentate complexes such as [FeL7 2(CH3CN)2]2+ are readily available.
Open vessel and cooling while heating microwave-assisted synthesis of pyridinyl N-Aryl hydrazones
La Regina, Giuseppe,Gatti, Valerio,Piscitelli, Francesco,Silvestri, Romano
experimental part, p. 2 - 6 (2011/04/15)
We reported the first example of open vessel and cooling while heating microwave-assisted synthesis of pyridinyl N-aryl hydrazones. Compounds were prepared in excellent isolated yields (88-98%) in only 5 min, by reacting 4- and 2,4-(di)substituted phenylhydrazines, bearing both electron-donating (4-CH 3, 4-OCH3) and -withdrawing (4-Cl, 4-Br, 4-CF3, 4-NO2, 2,4-Cl2) groups with 2-, 3-, and 4-acetylpyridine. The method was successfully extended to other carbonyl compounds.
