Eine neue Synthese von 4-Dimethylamino-1,3-butadien-1,1-dicarbonitrilen und deren Cyclisierung zu 2-Amino-3-cyanopyridinen

Synthesis, Coordination Chemistry and Bonding of Strong N‐Donor Ligands Incorporating the 1H‐Pyridin‐(2E)‐Ylidene (PYE) Motif

“…Ligand synthesis and characterisation: There are a limited number of methods for the preparation of hydrocarbyl-substituted PYEs, which have mainly relied on a cyclotrimerisation methodology, [4,[6][7][8][9]12] because the alkylation of 2-aminopyridine [2,3] is typically unselective and condensation reactions between 2-pyridinone and primary amines generally do not occur. Consequently, none of these methods are compatible with the synthesis of compounds containing multiple PYE motifs.…”

“…The angle between the planes defined by C(2)-C(1)-N(1) and C(1)-N(1)-C(7) for 11 is essentially equal (~6.88) to that in compound 7, and collectively, the structural features of 11 are similar to a related compound 1-methyl-2-(2'-pyridyl)-aminopyridinium chloride. [51] The 1 H NMR spectroscopic investigation shows four signals for the heterocycle that are significantly downfield from precursors 1, 5, and 9, respectively, whereas compound 11, for example, gives signals at 6 ), which are upfield from a typical unsubstituted pyridinium group such as N-methylpyridinium iodide. [57] A broad signal at 6.53 ppm is observed for the NÀ H(1) proton, however, the solubility of 12 and 13 restricted the solvents that could be used to obtain the NMR spectra to D 2 O or CD 3 OD, preventing the observation of analogous NH signals.…”

“…The variable-temperature spectra are consistent with a flipping motion of the PYE moieties above and below the palladium square plane through a C 2v intermediate, although it is unknown if the motion of the PYE moieties is correlated. At 163 K, the observation of only two signals for the linking (CH 2 ) 2 group rather than the four expected in a static system indicates (1) 2.2710 ( 178.13 (6) [a] The least-squares plane of the heterocycle containing C(1).…”

“…that some motion must still be present within the five-membered metallocycle. The reaction between 9 or 10 and 6 ] gave complexes 19 and 20 as diamagnetic light-brown and yellow solids, respectively (Scheme 4). The molecular structure of complex 20 was determined from single-crystal X-ray diffraction and is shown in Figure 6 and select data are given in Tables 2 and 4.…”

“…A pseudo-C 3 geometry is adopted by the ligand with the phenyl groups of the benzyl substituents at the periphery of the complex and benzylic hydrogen atoms towards the centre. An unusual feature is the position of the PF 6 À anion that is almost directly on the C 3 axis as illustrated by the angle N(7)-Cu(1)-P(1) = 1788, and there are three short contacts F(2) À H-A C H T U N G T R E N N U N G (30b) = 2.31, F(3) À HA C H T U N G T R E N N U N G (18a) = 2.50 and F(6) À H(6a) = 2.51 , potentially indicating directional cation/anion interactions. Furthermore, the remaining benzylic hydrogen atoms are approximately 2.28 from the copper centre.…”