Dual Role of Silanol Groups in Cyclopropanation and Hiyama-Denmark Cross-Coupling Reactions

Di-tert-butoxy(alkenyl)silanols serve as substrates in the Simmons-Smith cyclopropanation reaction furnishing the corresponding di-tert-butoxy(cyclopropyl)silanols, which may be included in a Hiyama-Denmark cross-coupling reaction. The silanol group bears two distinct roles as it provides a directing group during the cyclopropanation and mediates the transmetalation event in the cross-coupling. The nature of the ligands on the silicon atom had a profound effect on reactivity in the cross-coupling, whereby substituting the alkoxide groups for fluorides allowed for efficient cross-coupling.