Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via
1.1.1.5 Palladium-Catalyzed Intramolecular Hiyama Reactions and Applications

DOI: 10.1055/sos-SD-221-00001

Gao, S.; Wang, D.Science of Synthesis: Metal-Catalyzed Cyclization Reactions, (2016122.

Organosilicon reagents are generally stable and less reactive toward electrophiles than other organometallic nucleophiles because of their less-polarized C—Si bonds. Active pentacoordinate silicates are reactive species in the palladium-catalyzed Hiyama coupling reaction, and are normally prepared in situ by the nucleophilic attack of a fluoride ion on silicon,[‌54‌‌60‌] as shown in Scheme 14. This active hypervalent intermediate interacts with an R1—Pd(II)—X species, formed by oxidative addition of the organic halide to palladium(0), forming a four-membered cyclic transition state 25. The key transmetalation then occurs to generate R1—Pd(II)—R2, involving the migration of a reacting organic group (R2) from silicon to the palladium(II) center. The most commonly used activators for the formation of hypervalent silicates include tris(dimethylamino)sulfonium difluorotrimethylsilane (TASF) and tetrabutylammonium fluoride (TBAF).

Meeeee 88 Mee Meeeeeee Meeeeeeee ee Meeeeee-Meeeeeee Meeee-Meeeeeee Meeeeeeee

Meeeeee eee ee-eeeeeee eeee eeeeeee eee eeeeeeeee-eeeeeeeee eeeeeeeeeeeeee Meeeee eeeeeeee eeeeeeeee eeeeeee eeeee eeeeeee eee eeeeeeeeeeeeeeeeeeeee.[‌88‌,‌88‌] Me eee eeeee eeee eee eeeeeeeee eee eeeeee eeeeeeeee eeeeeeee eeeeeeee eeee eeeeeee eeee eee eeeeeee eeeeeee; ee eee eeeeeeee ee eeeeeeeee(8), eeeeee-eeeee eeeee eeee ee eeeeeeee M,M-8,8-eeeee eeee eee ee eeeeeeee ee eeee eeeee eee eeee eeee eeeeeeeeee-eeeee eeeeeeeeeeeee. Mee eeeeeeeeeeeee (8.88 M) eee eeee eeeeeeee eee eeeeeee eee eee eeeeeeeeeee ee eee eeeeee ee eeeee eeeeeeeee. Meeee eee eeeeeeeee eeeeeeeeee, eee eeeeeeeeeeeeee eeeeeeee ee eee eeeeeeeeee eeeee ee eee eeeeeeeee ee e eeeeee ee eeeeeeeeeeeeeee 88 (Meeee 8).

Meeee 8 Meeeeeeee-Meeeeeeee Meeeeeeeeeeeee Meeeee Meeeeeee Meeeeeeee[‌88‌,‌88‌]

Meeeeeeee Meeeeee(e) Meeee (%) Mee
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]
88 [‌88‌]

Meeeeee eee ee-eeeeeee eeeeeeeeeeee eeeeeeee eee eeeee eeeeeeeee ee (+)-eeeeeeeeeee eeeee eeee eeeeeeeeeee.[‌88‌,‌88‌] Me eeeee ee Meeeee 88, e eeee-eeeeeeee eeeeee eeeee eeeeeeee eeeeeeeeee e M,M-8,8-eeeee eeee eee eeeeeeeeeee eeeeeeeeeee eeeee eee eeeeeee eeeeeeeeee.

Meeeee 88 Meeee Meeeeeeee ee (+)-Meeeeeeeeee Meeee e Meeeee Meeeeeee Meeeeeee[‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeeeeeeee 88; Meeeeee Meeeeeeee:[‌88‌,‌88‌]

{Me(M8M8)Me}8 (8.888–8.88 eeeee) eee eeeeeeeee ee e eeee ee MMMM (88.8 eeeee) ee MMM eeeee e M8 eeeeeeeeee ee eeeeeee eeeeeeeeeee. Me eee eeeeeee eee eeeee eeeeee e 8.8 M eeee ee eee eeeeeeeeeeeeeeeeeeee eeeeeeeee ee MMM ee eeeeeee eeee. Meeee eeeeeeee eeeeeeee, eee eeee eeeee eeee eee eeeeeee eee ee eeeeeeeeee 8 e. Mee eeeeeee eee eeeeeee ee eeeeee eeeeeeeeeee eee MeMMe/eeeeee (8 eM) eee eeee eeeee. Mee eeeeeee eee eeeeeeee eeeeeee e eeeee eeeeee ee eeeeee eee, eeeee eee eeee eeeeee eeee MeMMe/eeeeee (888–888 eM). Mee eeeeee eee eeeeeeeeeeee ee eeeeee eeeeeeeeeee ee eeee e eeeee eeeeeee, eeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee) eeeeeeee ee Meeeeeeee eeeeeeeeeeee.

References


Cookie-Einstellungen