N,N-Disubstituted α-Amino-α,β-unsaturated Aldehydes and their Derivatives:1H and13C NMR Study

Abstract

1H and 13C NMR spectra of N,N‐disubstituted α‐amino‐α,β‐unsaturated aldehydes and their azomethines and enammonium salts were studied. The spectra reflect the degree of p–π conjugation between the nitrogen lone pair and the π‐electrons of the carbon–carbon double bond. In this respect, the title 2‐aminoenals are shown to be in an intermediate position between α‐unsubstituted aminoalkenes and α,β‐unsaturated aldehydes. The degree of conjugation depends on the nature of the amine moiety and the activating group. © 1997 John Wiley & Sons, Ltd.

The Wonderful Chemistry of Trifluoromethyl α‐Haloalkenyl Ketones

“…Evidently, the assembly of indenol derivatives is initiated by protonation of the carbonyl group in the enone 1 or 7 , followed by intramolecular electrophilic aromatic substitution resulting in the formation of the appropriate carbocycle 8 . In contrast, captodative aminoenones are generally reactive enough without any additional acid catalyst , …”

Regioselectivity Issues in the Addition of Grignard Reagents to Trifluoromethylated α‐Bromoenones

“…The predominant formation of the 1,4‐adducts from fluorinated substrates can be attributed to the influence of the strong electron‐withdrawing CF 3 group which contributes to reinforce the Michael acceptor character of the enone. In fact, trifluoromethylated α‐bromoenones 1 differ from their non‐fluorinated analogs α‐haloenones and enals as they have a sufficiently large positive charge on the olefinic β‐carbon and a higher carbon‐carbon double bond polarization , . As a result, among α,β‐unsaturated carbonyl compounds, trifluoromethylated α‐bromoenones are the most reactive Michael acceptors.…”

Hydrophosphonylation of α‐Haloalkenals

“…All the solvents were dried by standard procedures and freshly distilled prior to use. α‐Haloenals 1a–d were prepared by the halogenation–dehydrohalogenation sequence of the corresponding enals as reported previously .…”