We report quantum mechanics calculations and quasiclassical trajectory simulations of [4 + 2] reactions using three common dienolate substrates: siloxy dienes, Li dienolates, and conjugated Pd enolates. Asynchronous transition structures and unequal bond formation were invariably found, with average time gaps of developing bonds ranging from 26.5 to >251.0 fs. The results display a spectrum of dynamically concerted and stepwise [4 + 2] reactions, offering insights into the origin of the stereochemical outcomes of such reactions.

中文翻译：

---

二烯醇盐 [4 + 2] 反应的分子动力学研究

我们报告了使用三种常见二烯醇盐底物（硅氧基二烯、锂二烯醇盐和共轭钯烯醇盐）对 [4 + 2] 反应进行的量子力学计算和准经典轨迹模拟。总是会发现异步过渡结构和不等键形成，键形成的平均时间间隙范围为 26.5 至 >251.0 fs。结果显示了一系列动态协调和逐步的 [4 + 2] 反应，为了解此类反应的立体化学结果的起源提供了见解。