Umsetzung von β‐Chlor‐acroleinen mit Aminen

Abstract

Die Umsetzung von β‐Chlor‐3.4‐dimethoxy‐zimtaldehyd ergab mit Piperidin ein mesomeres, stabiles Imoniumchlorid, dessen weitere Reaktionen beschrieben werden. Der homologe β‐Chlor‐3.4‐dimethoxy‐α‐methyl‐zimtaldehyd gibt unter vergleichbaren Bedingungen das Aminal, unter energischen Bedingungen den β‐Piperidino‐aldehyd.

Novel Synthesis, Reactivity, and Stereochemistry of Substituted 3-Trifluoromethyl- and 3-Perfluoroalkyl-3-phenoxyprop-2-enal

“…The change of solvent did not affect the EE / ZE ratio; however, we observed a thermal isomerization of the stereoisomeric mixture in solution, and the percentage of the thermodynamically favored EE isomer increased 28b…”

“…For example, we found that enal 3c reacts easily with aniline and forms imine derivative 4 with good yields (94%) (Scheme ). Previously, the reaction of aniline with alkoxy vinyl ketones was studied, precluding a mechanism that involves a Michael addition of aniline with subsequent elimination of the alkoxy group and led to the corresponding enamino enone. 28b, In such enol ethers, the nucleophilic replacement of the alkoxy group is the predominant reaction. , In our case, only 1,2-addition product was observed probably because of steric hindrance of the perfluoroalkyl group and the high conjugation of compound 4 . To our knowledge, imino enol ether compounds have not been described yet in the literature.…”

“…According to the literature, compounds 3a − s can be characterized as push−pull ethylene derivatives. − Push−pull alkenes are substituted alkenes with one or two electron-donating substituents on one end of a CC double bond and with one or two electron-accepting substituents at the other end. Allowance for electron delocalization leads to the central CC bond becoming more polarized and with a lower barrier to rotation. , The push−pull effect is of decisive influence on both the dynamic behavior and the chemical reactivity of this class of compounds .…”

“…According to the literature, compounds 3a − s can be characterized as push−pull ethylene derivatives. − Push−pull alkenes are substituted alkenes with one or two electron-donating substituents on one end of a CC double bond and with one or two electron-accepting substituents at the other end. Allowance for electron delocalization leads to the central CC bond becoming more polarized and with a lower barrier to rotation. , The push−pull effect is of decisive influence on both the dynamic behavior and the chemical reactivity of this class of compounds . These olefins are often involved in isomeric equilibrium, which can be driven by heat,29a light, medium polarity, , or concentration. , It is expected that each isomer 3a − s can be described in term of Z / E isomerism for the C 2 C 3 double bond and around the C 1 −C 2 geometry (Scheme and ).…”

“…Allowance for electron delocalization leads to the central CC bond becoming more polarized and with a lower barrier to rotation. , The push−pull effect is of decisive influence on both the dynamic behavior and the chemical reactivity of this class of compounds . These olefins are often involved in isomeric equilibrium, which can be driven by heat,29a light, medium polarity, , or concentration. , It is expected that each isomer 3a − s can be described in term of Z / E isomerism for the C 2 C 3 double bond and around the C 1 −C 2 geometry (Scheme and ).

4 Stereochemical Assignment of 3d EE and ZE Using Coupling Constants

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