Stereodivergency in Copper‐Catalyzed Borylative Difunctionalizations: The Impact of Boron Coordination

A reagent‐controlled diastereodivergent copper‐catalyzed borylative difunctionalization is reported. The formation of Lewis adducts that guide selectivity is commonly invoked in organic reaction mechanisms. Using density functional theory calculations, we identified BpinBdan as a sterically similar and less Lewis acidic alternative to B2pin2. Using a newly developed borylative aldol domino reaction as the proof‐of‐concept, we demonstrate a change in stereochemical outcome by a simple change of borylating reagent—B2pin2 affords the diastereomer associated with coordination control while BpinBdan overturns this mode of binding. We show that this strategy can be generalized to other scaffolds and, more importantly, that BpinBdan does not alter the diastereomeric outcome of the reaction when coordination is not involved. BpinBdan can be viewed as a mechanistic probe for coordination in future copper‐catalyzed borylation reactions. A copper‐catalyzed stereodivergent borylative difunctionalization strategy is reported. The key component in obtaining stereodivergence lies in the Lewis acidity of the introduced boron group. The more Lewis acidic Bpin group enables chelation control affording an all cis diastereomer. Conversely, the less acidic Bdan group overrides this preference by disfavouring adduct formation, leading to a bifurcation in the stereochemical outcome.