在生物衍生性脚手架上的分子间胺Mizoroki-Heck反应

α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.

Enamine formation involves the addition of carbonyl compounds to a secondary amine through a series of reactions. The mechanism begins with the generation of carbinolamine, a nucleophilic attack followed by several proton transfer reactions. The hydroxyl group of the carbinolamine is converted into water to make a better leaving group that can push the reaction forward by eliminating a water molecule. In enamine formation, the last step involves the abstraction of a proton from the α carbon to...

Primary amines react with carbonyl compounds—aldehydes and ketones—to generate imines. Imines consist of a C=N double bond and are named Schiff bases after its discoverer—the German chemist Hugo Schiff. On the other hand, secondary amines react with carbonyl compounds to give enamines. In enamines, the presence of a C=C double bond adjacent to the nitrogen atom leads to the delocalization of the lone pair.

Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A carbonyl compound with an α hydrogen undergoes keto–enol tautomerism and remains in equilibrium with its tautomer, the enol form. Usually, the keto tautomer is present in a higher concentration than the enol tautomer due to the higher bond energy of C=O compared to C=C. Moreover, the direction of the keto–enol equilibrium is...

Alkenes can be obtained from amines via an E2 elimination. The amine is first converted into a good leaving group, such as a quaternary ammonium salt. This is accomplished by treating the amine with an excess of alkyl halide, which results in a halide salt. Next, the halide salt is transformed into a hydroxide salt that functions as a base to enable elimination.
Under thermal conditions, the hydroxide can abstract a proton from the β carbon; this generates an alkene with the simultaneous...

Aldehydes and ketones form enols, although only about 1% of the enol is present at the equilibrium for simple monocarbonyl compounds. The enol form is undetectable for acetaldehyde, present as only 1.5 × 10−4 % of acetone, and present as only 1.2% of cyclohexanone. Two kinds of regioisomeric enols are possible for unsymmetrical ketones, and their net composition is 1% at equilibrium. This instability is due to the lower bond energy of C=C than the C=O group. The additional...