The Prins reaction is an organic reaction used to convert an alkene and an aldehyde to a variety of products depending on the reaction conditions. (6S)-Hexahydro-1,4-oxazepin-6-ol Purity Dabigatran uses All mechanisms begin with protonation of the aldehyde which is then attacked by the alkene to give a β-hydroxyl carbocation intermediate. Without the addition of other reagents this intermediate will react with water in an elimination reaction to give an allylic alcohol product. If nucleophiles are added to the reaction mixture they would directly attack the carbocation to give an alcohol, while if excess of the aldehyde reagent is used, the reaction will result in a 1,3-dioxane. ^[1][2]