Depending on the reaction conditions the intramolecular Diels-Alder reaction of furan-diene yields predominantly either one of two adducts and , which possess the necessary functionality for eventual transformation into corticosteroids. The dienophile was introduced via alkylation
![[3-(furan-2-yl)-2-methylcyclopenten-1-yl]oxy-trimethylsilane Structure](https://image.chemsrc.com/caspic/299/83669-69-6.png)