Electronic spectra of .alpha.,.beta.-unsaturated carbonyl compounds. I. An evaluation of increments characteristic of changes in configuration (cis/trans) and conformation (s-cis/s-trans) based on direct observation of the isomerization of enamino aldehydes and ketones
Regioselective reactions of enaminones with enones—II
作者:Lech Kozerski、E. Czerwinska、T. Pobiedzinska
DOI:10.1016/0040-4020(82)80202-0
日期:1982.1
Intramolecular dynamic behaviour helps in predicting the regioselectivity of reactions in ambident molecules. Thus the enaminones (1) react on the C-2 carbon atom with benzoquinone. Reaction proceeds with an intramolecular acyl shift following formation of the initial reaction complex upon reaction at position C-2 of the enaminone and the quinone. Under certain conditions the reaction is regiospecific
NMR of enaminones. Part 8—1H, 13C and 17O NMR spectra of primary and secondary 1,2‐disubstituted enaminones: configuration, conformation and intramolecular hdydrogen bonding
The H-1,C-13 and O-17 NMR spectra for four series of C-2-substituted enaminones are reported: MeCO(Me)C=CHNHR (1), EtCO(Me)=CHNHR (2), PhCO(Me)C=CHNHR (3) and MeCO(Me)C=CHNHR (4). The H-1, C-13 and O-17 NMR data for these enaminones show that 1 and 2 exist as mixtures of E- and Z-forms, 3 exists mainly in the E-form and 4 is in the Z-form. The E- and Z-forms exist in the E-s-E-s-E and Z-s-Z-s-E conformations, respectively. The O-17 shift values of the carbonyl groups in the four series of enaminones show that the influence of N substituents is essentially identical and is additive. The shielding of the carbonyl O atom by intramolecular hydrogen bonding (Delta delta(HB)), ca. - 30 ppm, is dependent on the donor ability of the amino groups and the type of C-l and C-2 substituents. Correlations of the H-1, C-13 and O-17 NMR data between the E- and Z-forms of enaminones are excellent. (C) 1998 John Wiley & Sons, Ltd.
KUCKLANDER, UWE;KUNA, KRYSTINA, CHEM. BER., 120,(1987) N 9, 1601-1602
作者:KUCKLANDER, UWE、KUNA, KRYSTINA
DOI:——
日期:——
Electronic spectra of .alpha.,.beta.-unsaturated carbonyl compounds. I. An evaluation of increments characteristic of changes in configuration (cis/trans) and conformation (s-cis/s-trans) based on direct observation of the isomerization of enamino aldehydes and ketones