0000000000138942
AUTHOR
Agnieszka Skotnicka
NMR studies of benzoannulation in lithium, sodium and potassium ortho-formylphenolates
Abstract Lithium, sodium and potassium derivatives of (benzo)salicylaldehydes have been prepared and characterized by 1 H and 13 C NMR in order to see how the metal cation and benzoannulation affect spectral parameters. There is no qualitative effect of the alkali metal atom in the compounds studied (from this point of view salicylaldehydes remind β-diketones). On the other hand, 1 H chemical shifts of the hydroxyl and formyl protons and 13 C chemical shifts of C2 (bearing OX, X = H, Li, Na or K) and of that the formyl carbon show the most significant variations being the best indicators of aromatic character of the six-membered quasi-ring of salicylaldehyde. In contrast, C1 (bearing formyl…
2-[4-(Dimethylamino)phenyl]-3,3-difluoro-3H-naphtho[1,2-e][1,3,2]oxazaborinin-2-ium-3-uide
In the title compound, C19H17BF2N2O, a twist about the N—C single bond is observed, making the cross conjugation not as efficient as in the case of a planar structure. The borone complex has tetrahedral geometry. In the crystal, molecules are conected by weak C—H...F hydrogen bonds.
2-Methyl-4-phenyl-3,4-dihydroquinazoline
The title compound, C15H14N2, was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7)°. In the crystal, intermolecular N—H...N interactions connect the molecules into infinite chains.
Synthesis and Structural Characterization of Substituted 2-Phenacylbenzoxazoles
1 H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl3-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1 H NMR signals were used to evaluate the molar ratio of the tautomers. Strong electron-donating substituents were found to stabilize the ketimine tautomer. pKT (negative logarithm of the equilibrium constant, KT = [ketimine]/[enolimine]) was found to be linearly dependent on the Hammett substituent constant σ. The results of the MP2 ab…
CCDC 922097: Experimental Crystal Structure Determination
Related Article: Agnieszka Skotnicka, Erkki Kolehmainen, Przemysław Czeleń, Arto Valkonen, Ryszard Gawinecki|2013|Int.J.Mol.Sci.|14|4444|doi:10.3390/ijms14034444
CCDC 922098: Experimental Crystal Structure Determination
Related Article: Agnieszka Skotnicka, Erkki Kolehmainen, Przemysław Czeleń, Arto Valkonen, Ryszard Gawinecki|2013|Int.J.Mol.Sci.|14|4444|doi:10.3390/ijms14034444
2-Methyl-4-phenyl-3,4-dihydroquinazoline
The title compound, C15H14N2, was formed during the lithiation of 2-methylquinazoline with phenyllithium followed by hydrolysis of the intermediate lithium 2-methyl-4-phenyl-4H-quinazolin-3-ide. NMR spectra as well as single-crystal X-ray structural data indicate that the reaction product to have the same structure in chloroform solution as in the crystalline state. The phenyl substituent is twisted out of the plane of the 3,4-dihydroquinazoline ring system by 86.47 (7)°. In the crystal, intermolecular N-HN interactions connect the molecules into infinite chains. peerReviewed