Related Experiment Video
Updated: Apr 21, 2026

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Why alkynyl substituents dramatically accelerate hexadehydro-Diels-Alder (HDDA) reactions: stepwise mechanisms of
Yong Liang1, Xin Hong, Peiyuan Yu
1Department of Chemistry and Biochemistry, University of California , Los Angeles, California 90095, United States.
Abstract:
The hexadehydro-Diels-Alder (HDDA) reactions between suitably substituted 1,3-diynes and alkynes produce highly reactive benzynes under thermal conditions without catalysts. DFT calculations and distortion/interaction analyses show that, for the activated substrates, the stepwise diradical pathway is more favorable than the concerted [4 + 2] process. One manifestation of this mechanism is that alkynyl substituents dramatically accelerate HDDA reactions, mainly by decreasing the distortion energy required to achieve the diradical transition state.
More Related Videos
09:35Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
11:44Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
Related Concept Videos
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Diels–Alder Reaction: Characteristics of Dienophiles
Characteristics of Dienophiles
Generally, the best dienophiles are alkenes containing electron-withdrawing substituents such as carbonyl, nitrile, and nitro groups. The feasibility of a Diels–Alder reaction...
Diels–Alder Reaction: Characteristics of Dienes
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is...
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
E1 Reaction: Kinetics and Mechanism
Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry