Heterocyclization of N-aryl-2-naphthylamines with formaldehyde and dimedone in the presence of HCl and HBr

Kornilov, M. Yu.; Туров, А. В.; Melnı́k, Milan; Gutsulyak, B. M.

doi:10.1007/bf00472486

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“…(1) for LRS-induced proton shifts was minimal. Just that point was characterized by the best agreement between the calculated and experimental lanthanide-induced shifts [7]. We succeeded in determining the structure of Yb(fod) 3 adducts with chalcones IXVI with a high statistical reliability.…”

Section: Andrps Qr /65mentioning

confidence: 97%

Conformational Mobility of Substituted 2-Methoxychalcones under the Action of Lanthanide Shift Reagents

et al. 2005

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Various lanthanide shift reagents Ln(fod) 3 were found to affect the conformational composition of 2-methoxychalcones. Coordination of Yb(fod) 3 occurs mainly at the carbonyl oxygen atom of the substrate, while Eu(fod) 3 and shift reagents derived from other lanthanides coordinate substituted chalcones as bidentate ligands, giving rise to a secondary tetrachelate with the corresponding change of conformation of the substrate molecule. The possibility for chelation is determined by steric hindrances in the vicinity of the substrate coordination centers and concurrent coordination of other electron-donor groups present in the substrate molecule.Lanthanide shift reagents (LSR) have long been used in structural and conformational analysis of organic compounds, studies of their chirality, and interpretation of the NMR spectra. Creation of superconducting spectrometers made it possible to solve many problems without involving LSR. In the recent years, new fields of application of LSR were found, e.g., enhancement of regioselectivity of organic reactions [1], analysis of ion ion interactions [2], and experimental determination of the site of predominant charge localization in anions [3]. The effect of LSR on conformations of difunctional compounds was revealed recently [4]. Although this property of LSR can complicate their use as conformational probes, it may be helpful in modeling interactions between small molecules and biological macromolecules, where biological activity of a small molecule originates from variation of its conformation during association. Therefore, studies on the effect of LSR on molecular conformations in solution seem to be important.Application of LSR is based on their ability to selectively coordinate electron-donor functional groups in the substrates and induce shifts of signals in the NMR spectra; the magnitude of the lanthanide-induced shifts depends on the structure of the LSRsubstrate adduct and arrangement of magnetic nuclei in the substrate molecule relative to the coordination center [5,6]. The structure of LSR adducts with monofunctional organic molecules was extensively studied [7].Complex formation of LSR with difunctional compounds is characterized by some specific features. Most frequently, coordination centers present in a substrate molecule operate independently from each other, and the induced shifts are integral quantities for all possible adducts. If coordination centers in a substrate molecule are spatially close, chelation with LSR is possible to afford tetrakis-adducts in which the coordination number of lanthanide increases to 8 [8]. In order to study this mode of coordination in more detail, we synthesized a series of substituted 1-(2'-alkoxyphenyl)-3-phenyl-2-propenones 5 5 5 5 2 5 5 5 $ , B ;9, D % IXVI, R x = H, unless otherwise stated; I, R 1 = OCH 3 , R 3 = Cl, R 7 = F; II, R 1 = OCH 3 , R 3 = R 5 = Cl; III, R 1 = OCH 3 , R 3 = Br, R 5 = Cl; IV, R 1 = OC 2 H 5 , R 3 = R 7 = Cl; V, R 1 = R 5 = OCH 3 , R 3 = Cl; VI, R 1 = OCH 3 , R 3 = Cl, R 6 R 7 = OCH 2 O; VI...

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Section: Andrps Qr /65mentioning

confidence: 97%