Electrophilic Activation of Benzaldehydes through ortho Palladation: One‐Pot Synthesis of 3‐Methylene‐indan‐1‐ols through a Domino Allylstannylation/Heck Reaction under Neutral Conditions

Active neighbors : The Pd‐catalyzed reaction of ortho ‐iodo‐ and ortho ‐trifluoromethanesulfonyloxy(OTf)benzaldehydes with allyltributylstannane gives 3‐alkylidene‐1‐indanols (see scheme). The allylation/Heck reaction involves a new catalytic activation mode: the electrophilic activation of an aldehyde group by a Lewis acidic Pd II center generated at the ortho  position by oxidative addition. Alkoxystannanes serve as a base equivalent, allowing Heck‐type transformations under neutral conditions.