Palladium-Catalyzed Alkylation with Alkyl Halides by C(sp3 )-H Activation

Abstract

Utilizing halogens as traceless directing goups represents an attractive strategy for C-H functionalization. A two C-H alkylation system, initiated by the oxidative addition of organohalides to Pd⁰ , has been developed. The first reaction involves an intermolecular alkylation of palladacycles to form C(sp³ )-C(sp² ) bonds followed by C(sp² )-H activation/cyclization to deliver alkylated benzocyclobutenes as the final products. In the second reaction, two C-C bonds are formed by the reaction of palladacycles with CH₂ Br₂ , and provides a facile and efficient method for the synthesis of indanes. The alkylated benzocyclobutene products can be transformed into tricyclic hyrocarbons, and the indane derivatives are essential structural motifs in bioactive and odorant molecules.

Keywords: C−H activation; alkylation; arenes; cyclization; palladium.