A strategic approach for Csp3-H functionalization of 9H-fluorene: an acceptorless dehydrogenation and borrowing hydrogen approach

Herein, we described the selective synthesis of both alkylated and alkenylated fluorenes using a single SNS ligand derived nickel complex. The protocol was employed for a wide range of substrates, including substituted fluorenes and various alcohols including aliphatic alcohols with a distal double bond. To expand the synthetic utility, an antimalarial drug analogue, benflumetol, was synthesized, and various post-modifications of alkylated fluorenes to their corresponding epoxides, amino alcohols, and boronate esters were demonstrated. Control experiments and kinetic profile diagrams depict that the reaction works via an unsaturated intermediate and proves the involvement of the borrowing hydrogen approach.