Selective Synthesis of Boron-Functionalized Indenes and Benzofulvenes by BCl 3 -Promoted Cyclizations of ortho -Alkynylstyrenes.

A selective, metal-free synthesis of boron-functionalized indenes and benzofulvenes via BCl 3 -mediated cyclization of o -alkynylstyrenes is described. The method allows precise control over product formation by adjusting reaction conditions. These borylated products were utilized in diverse C-B bond derivatizations and in the total synthesis of Sulindac, a nonsteroidal anti-inflammatory drug, demonstrating the versatility and practicality of the developed methodology for synthetic applications.