Action d'agents nucleophiles sur les 4-arylideneisoxazoline-5-ones, synthese et etude de la stereoisomerie de 4-cinnamylideneisoxazoline-5-ones.

4-Arylmethylisoxazol-5-one Derivatives − Novel Synthesis, Structural Studies, and Supramolecular Self-Assembly through Resonance-Assisted Hydrogen Bonding

“…The IR and 1 H NMR spectra were identical to and superimposable on those of 3 [6] and 4, [8] reported previously.…”

“…All the 4-arylmethyl derivatives 3 were unequivocally identified by comparison with known authentic samples, while the structural assignment of 4-(cinnamylidene)isoxazolones 4 was based on analytical and spectroscopic data and confirmed by comparison of their IR and 1 H NMR spectra and those of analogous derivatives previously studied by one of us. [8] It is evident, therefore, that the isolation of DEA (5), which was characterised by gas chromatography, and the formation of cinnamylidene derivatives 4 through insertion of an ethylene unit into the exocyclic double bond of 1 clearly indicate the involvement of an ethyl group in the starting TEA. To confirm this, the reaction was repeated with the substrate 1a and other selected tertiary amines.…”

Iminium Salts of ω-Dithiafulvenylpolyenals: An Easy Entry to the Corresponding Aldehydes and Doubly Proaromatic Nonlinear Optic-phores

“…As judged from 3 J HH values, iminium salts 2b , c have an all - trans geometry, like the corresponding aldehydes 1b , c . Similarly, 1 H NMR spectra of 7a − c in CDCl 3 reveal an all - trans configuration of the polyenic chain, except for the CC bond formed in the Knoevenagel reaction, which has ( Z )-geometry as shown by the strong deshielding experienced by the H atom located five bonds away from the carbonyl oxygen atom . This assignment was confirmed by an X-ray diffraction study of single crystals of 7a .…”

4H-Pyran-4-ylidenes: Strong Proaromatic Donors for Organic Nonlinear Optical Chromophores

“…Concerning compounds 1 − 5 , 3 J HH coupling constants analysis along the spacer shows that CHCH and CH−CH bonds have ( E )-configuration and s - trans conformation, respectively. On the other hand, the isoxazolone-exocyclic CC bond in compounds 2 has a ( Z )-geometry, as demonstrated by the downfield shift of the H atom located five bonds away from the carbonyl oxygen atom. , Similarly, the HCC(CN) bond in compounds 3 (see below) shows the expected ( Z )-geometry. Concerning compounds 4 , NOE and NOESY experiments at different temperatures on model compound 4b did not allow to establish the configuration of the HCC(CN) bond, but previous studies on related compounds show a ( Z )-geometry for that fragment, configuration that is also assumed for 4 …”