Name: heck reaction: mechanism
Uploaded: 2023-01-10T17:30:47
Description: In the Heck reaction, the vinylic hydrogen of alkene is substituted with the organyl group of an organohalide to form a substituted alkene in the presence ...

The Heck reaction mechanism involves a catalytic cycle with five main steps: oxidative addition, syn addition, C&#8211;C bond rotation, syn elimination, and reductive elimination.
The reaction begins with the oxidative addition of an organohalide to an active Pd(0) catalyst to form a tetra coordinated organopalladium(II) complex.
This complex then adds across the double bond of the starting alkene by syn addition. The intermediate so formed has the organyl group attached to the less substituted carbon atom.
The intermedi...

heck reaction: mechanism

In the Heck reaction, the vinylic hydrogen of alkene is substituted with the organyl group of an organohalide to form a substituted alkene in the presence of palladium (Pd) catalyst and base. The mechanism of the Heck reaction involves a catalytic cycle comprising five steps: Oxidative addition, syn addition, carbon&#8211;carbon rotation, syn elimination, and reductive elimination.
First, the oxidative addition of organohalide to the active Pd(0) catalyst results in a tetra coordinated Pd(II) complex. In the second step, syn addition of the Pd(II) complex takes place across the &#960; bond of alkene to form a Pd(II) adduct. The addition occurs such that the organyl group is attached to the less substituted carbon while the Pd group is attached to the more substituted carbon. Further, an internal conformational change takes place whereby carbon&#8211;carbon bond rotation occurs, placing H and the Pd group on the same side. Later, syn elimination results in the elimination of H and the Pd group along with the release of new substituted alkene. During reductive elimination, the base neutralizes acid while simultaneously regenerating the active Pd(0) catalyst, which then enters the next catalytic cycle.
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Heck Reaction: Mechanism

In the Heck reaction, the vinylic hydrogen of alkene is substituted with the organyl group of an organohalide to form a substituted alkene in the presence ...