After exploring the scope of this reaction, we started to study the reaction stereoselectivity in the first allylic substitution. Starting from diastereoenriched substrate 1o (dr = 16:1), the Lewis acidcatalyzed reaction proceeded with poor diastereoconservation (Scheme 4A). Remarkably, only one regioisomer was observed in this reaction. Similarly, from enantioenriched 1f, the product 3b was obtained with poor enantioconservation. Nevertheless, we could exploit the absence of stereospecificity by performing diastereoselective reactions starting from secondary alcohols (Scheme 4B). The diastereoselectivity ranged from moderate for methyl-substituted secondary alcohols (2ab, dr = 3:1) to good in the case of cyclohexyl or isopropyl substituents (2ac, 2ad, 2af) to excellent in the case of more sterically demanding tert-butyl substituents (2ae, dr > 20:1). Secondary benzyl alcohol led to the desired THF product in lower yield and poor diastereoselectivity. We wondered whether the first step could proceed using a different orthoester as activator. We were pleased to observe that upon treatment of 1a with trimethyl orthobenzoate and catalytic amount of BF3•Et2O the cyclisation occurred, affording allylic benzoate 3c (Scheme 5A). We were also interested by the use of hard nucleophiles in order to expand the scope of the second substitution (Scheme 5B). Unfortunately, the one-pot double allylic substitution did not proceed using phenyl magnesium bromide as the second nucleophile. Starting from intermediate 3d resulting from the first allylic substitution, the reaction mainly led to decomposition and only 12% of the desired product 2ah was observed. On the other hand, using one equivalent of copper cyanide instead of the palladium catalyst allowed conversion of triol 1a into 2ah efficiently. This result is particularly surprising given the precedents suggesting that presence of copper promotes an SN2' type reaction. A deeper study on this reaction mechanism is currently ongoing. We also decided to showcase the utility of our method by achieving the synthesis of dienyl-THF structure 4. For that, the product 2aa was subjected to modified Julia olefination conditions. Dienyl-THF structures are particularly relevant as they can be found in various fungal metabolites, and are also involved in the biosynthesis of diverse natural products. Scheme 5. Miscellaneous observations.