Development of a General Method for the Hiyama–Denmark Cross-Coupling of Tetrasubstituted Vinyl Silanes

Abstract

General conditions for the Hiyama−Denmark crosscoupling of tetrasubstituted vinyl silanes and aryl halides are reported. Prior reports of Hiyama−Denmark reactions of tetrasubstituted vinyl silanes have required the use of vinyl silanols or silanolates, which are challenging to handle, or internally activated vinyl silanes, which lack structural generality. Now, unactivated tetrasubstituted vinyl silanes, bearing bench-stable tetraorganosilicon centers, and aryl halides can be coupled. The key to this discovery is the identification of dimethyl(5-methylfuryl)vinylsilanes as bench stable and easily prepared cross-coupling partners that are readily activated under mild conditions in Hiyama−Denmark couplings. These palladium-catalyzed cross-couplings proceed well with aryl chlorides, though aryl bromides and iodides are also tolerated, and the reactions display high stereospecificity in the formation of tetrasubstituted alkenes. In addition, only a mild base (KOSiMe 3 ) and common solvents (THF/DMA) are required, and importantly, toxic additives (such as 18-crown-6) are not needed. We also show that these conditions are equally applicable to Hiyama−Denamrk coupling of trisubstituted vinyl silanes.

Photocatalyzed Thiosulfonylation of Sila-enynes with Thiosulfonates

“…The main reason is that extra 3d orbitals of elemental silicon easily interact with heteroatoms and metal ions to form hypervalent five- or six-coordinated intermediates, leading to the decomposition of organosilicanes . Meanwhile, transmetalation between sila-compounds and metal catalysts could possibly occur to make the silane-based chemical reactions more challenging . Therefore, exploration of an efficient approach to combine versatile groups into sila-scaffolds is always desirable.…”

Cross‐Coupling Reactions between Arenediazonium o‐Benzenedisulfonimides and Organolithium Reagents in a Deep Eutectic Solvent

“…These reactions usually involve the coupling of an organic halide as the electrofile with an organometallic compound. Organoboron (Suzuki‐Miyaura coupling), [2] organozinc (Negishi coupling), [3] organotin (Stille coupling), [4] organosilicon (Hiyama‐Denmark coupling), [5] organomagnesium (Kumada coupling) [6] have been (and are) widely and universally used. Conversely, organolithium compounds (Murahashi coupling) [7] were employed much more rarely, although they are cheap and easily available.…”