FeCl3•6H2O and TfOH as Catalysts for Allylic Amination Reaction: A Comparative Study

The use of FeCl3 center dot 6H(2)O and TfOH as readily available and easy-to-handle catalysts for the direct allylic amination reaction using a wide variety of nitrogenated nucleophiles onto different free allylic alcohols is described. Comparative studies between these catalysts, as representative Lewis and Bronsted acids are conducted, concluding that both are suitable catalysts for this transformation. The reactions are performed in a flask open to air and using technical grade 1,4-dioxane. In light of the results obtained from this study it can be asserted that TfOH turned out to be slightly superior than the FeIII salt since similar or better yields are obtained in most of the cases using lower catalyst loadings and milder reaction conditions. A similar trend is observed when carbonucleophiles were employed in the allylic substitution reaction. Studies for the elucidation of the reaction mechanism are in agreement with a carbocationic intermediate, being the regioselectivity governed by the stability of the final product.