Theoretical Analysis of Reactivity Patterns in Diels–Alder Reactions of Cyclopentadiene, Cyclohexadiene, and Cycloheptadiene with Symmetrical and Unsymmetrical Dienophiles

Abstract

The Diels-Alder reactions of cyclopentadiene, cyclohexadiene, and cycloheptadiene with a series of dienophiles were studied with quantum mechanical calculations (M06-2X density functional theory) and analyzed with the distortion/interaction model. The poor reactivities of cyclohexadiene and cycloheptadiene with dienophiles that give relatively synchronous transition states result from the substantial distortion required to achieve a transition state involving the formation of two bonds of the diene simultaneously. However, highly asynchronous or stepwise reactions result in less distortion of the diene and less differences in reactivities of different dienes. The transition state geometry of cyclopentadiene is less distorted in the asynchronous reaction with 1,1-dicyanoethylene compared to that with cis- and trans-1,2-dicyanoethylenes, which react through synchronous transition states.

Schleyer hyperconjugative aromaticity and Diels–Alder reactivity of 5‐substituted cyclopentadienes

“…The reactivities of cyclopentadienes are controlled by the energy required to distort the diene from a planar to envelope geometry, and the change in θ C5X that accompanies this change. In the transition states of dienes 1–6 , θ C5 ranges from 17 to 20°.…”

Research Progress on the Synthesis and Application of Cyclopentadiene Derivatives

“…此外, 经修饰后的环戊二烯酮聚合物在可见 光波长范围内有较强的吸收带, 在太阳能电池方面有很 好的应用前景, 可用于制备的本体异质结器件. 4 与卤化氢进一步反应生成了具有光敏感 度的{Fe(cis-CO) 2 }化合物(Eq. 9), 并指出其光敏感性与 配体有关.…”

“…环戊二烯及其衍生物可以进行聚合 [1] 、氢化还 原 [2] 、氧化 [3] 、加成 [4,5] 和扩环 [6] 等反应, 在茂化合物、树 脂、农药、橡胶、阻燃剂、医药和光电器件领域等领域 已得到广泛应用 [7～9] . 溶剂中, 80 ℃和钯催化条件下将 4-羟基取代的香豆素 和二苯乙炔环化生成得到化合物 1 (Eq.…”

Understanding the Regioselective and Molecular Mechanism of the TCE in Cycloaddtion Reaction (TCE+Cp) and Addition Reaction (TCE+HCl) using DFT calculation

“…The extent of the asynchronicity can be measured from the difference between the distances, d1 and d2, of the two new single bonds, which are being formed at the TSs, Δd = d1 -d2. [40,41] The values of Δd for TS1, TS2, TS3 and TS4 are 0, 1.70, 1.38 and 1.33 A, respectively. Considering the calculated Δd values, it is obvious that the most favorable TS1 displays the highest degree of asynchronicity.…”