Alkylation‐Terminated Catellani Reactions Using Alkyl Carbagermatranes

The Catellani reaction has received substantial attention because it enables rapid multiple derivatization on aromatics. While using alkyl electrophiles to achieve ortho‐alkylation was one of the earliest applications of the Catellani reaction, ipso‐alkylation‐terminated reactions with β‐H‐containing reactants has not been realized to date. Herein, we report alkylation‐terminated Catellani reaction using alkyl carbagermatranes (abbreviated as alkyl‐Ge) as nucleophiles. The reactivity of alkyl‐Ge and alkyl‐B(OH)2 in this reaction is discussed. This approach enables efficient dialkylation with β‐H‐containing reactants, which was previously inaccessible by Catellani reactions. Alkylation‐terminated Catellani reactions have not been well developed mainly due to the significant challenge of the transmetalation of β‐H‐containing alkyl groups onto the sterically hindered aryl‐PdII intermediate. In this work, this challenge was overcome by using highly efficient alkyl‐Ge nucleophiles as terminating reagents.