The Diels-Alder reaction was first reported by Diels and Alder in 1928. The first use of this reaction in a total synthesis was not reported until 1952 (Woodward synthesis of cholesterol) – two years after the Nobel Prize was awarded to Diels and Alder. The original discovery by Diels and Alder involved the reaction between cyclopentadene and quinone. Interestingly, the Woodward synthesis of cholesterol also involved a quinone. The first step of the Woodward cholesterol synthesis is shown below:
The Virtual Molecular Model Kit Action Page for this post works with models of 1,3-butadiene and ethene – the simplest Diels Alder reaction. The models are loaded as Spartan files that contain coordinate data, charge data, and molecular orbital data. The page will explore the the model kit’s use of this data, including a visualization of Frontier Molecular Orbital Theory as it apples to the Diels Alder reaction.