Secondary amines react with carbonyl compounds to form enamines
المؤلف:
Jonathan Clayden , Nick Greeves , Stuart Warren
المصدر:
ORGANIC CHEMISTRY
الجزء والصفحة:
ص233-234
2025-05-14
623
Pyrrolidine, a secondary amine, reacts with isobutyraldehyde, under the sort of conditions you would use to make an imine, to give an enamine. The name enamine combines ‘ene’ (C=C double bond) and ‘amine’.
The mechanism consists of the same steps as those that take place when imines form from primary amines, up to formation of the iminium ion. This iminium ion has no N–H proton to lose, so it loses one of the C–H protons next to the C=N to give the enamine. Enamines, like imines, are unstable to aqueous acid.
●Imines and enamines
• Imines are formed from aldehydes or ketones with primary amines.
• Enamines are formed from aldehydes or ketones with secondary amines. Both require acid catalysis and removal of water.
Enamines of primary amines, or even of ammonia, also exist, but only in equilibrium with an imine isomer. The intercom-version between imine and enamine is the nitrogen analogue of enolization, which is discussed in detail in Chapter 20.
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