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
26.9.1.1.3.6 Variation 6: Transition-Metal-Catalyzed Coupling of Alkenylmetals with Carboxylic Acid Halides and Anhydrides

DOI: 10.1055/sos-SD-026-00987

Marsden, S. P.Science of Synthesis, (2005261056.

Palladium(II)acyl complexes can be generated by the insertion of zerovalent palladium into the carbonhalogen bond of acid halides. In the presence of suitable organometallic donors, transmetalation and reductive elimination occurs, yielding enones. Alkenylstannanes are viable donors and the mild nature of the method is demonstrated by the successful formation of potentially base-sensitive products such as 54 (Scheme 13).[‌52‌] Alkenylzincs such as 55 are also good coupling partners,[‌53‌] and alkenylcoppers[‌41‌] and aluminums[‌54‌] can also be used. Decarbonylation of the intermediate palladium(II)acyl complexes can be a competing reaction, leading to alkene rather than enone products. Carrying out the reactions under an atmosphere of carbon monoxide can minimize this process.[‌55‌] Alkenylboronic acids such as 56 are popular choices as nucleophilic coupling partners in transition-metal-mediated reactions owing to their stability and ease of handling. They are converted into enones by coupling with thiol esters under palladium catalysis in the presence of copper(I) thiophene-2-carboxylate as an activating agent.[‌56‌] Rhodium(I) catalysts also promote the addition of alkenylboronic acids to acid anhydrides, to give products such as 57.[‌57‌] The mechanism of this latter process likely involves direct addition of an alkenylrhodium species to the anhydride.

Meeeee 88 Meeeeeeeee-Meeee-Meeeeeeee Meeeeeee ee Meeeeeeeeeeee eeee Meeeeeeee Meeeee[‌88‌,‌88‌,‌88‌,‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeee 8-Meeeeee-8-eeeeee (88); Meeeeee Meeeeeeee:[‌88‌]

MMMMMMM: Meeeeeeeeeeeeeeeeeee eeeeeeee ee e eeeeeeee eeeee eeeeeeeeee eee ee eee eee eeee eeeeeeee.

Meeeeeee MMMM ee eeeeeeee ee ee eee eeee eeeeeeeee eeeeeee eee eeee eeeeeeeeeeeeee, MMM eee eeee ee eeee.[‌88‌] Meeeeeee(eeeee)eeeeeeee (8.8e, 88.88eeee) eee MeMeMe(MMe8)8 (88.8ee, 8.888eeee) eeee eeeee ee e eeee ee eeeeee eeeeeeee eeeeeeee (8.8e, 88.88eeee) ee MMMM (8eM). Mee eeeee eeeeee eeee eee eeeeee ee 88°M eeee eeeeeeee eeeee eee eee eeeee 8eee ee eeeeeeeeeeeee eeeee eeeeee ee eeeee eeeeeeee. Mee eeee eee eeeeee ee ee eee M8M (88eM) eee eeeee. Meeee MeMe (ee. 8e) eee eeeee ee eee eeeeeee, eeeee eee eeee eeeeeeeee eeee Me8M (8×88eM). Mee Me8M eeeeeeee eeee eeeeeeee, eeeeee eeee M8M (8×88eM), eee eeeee (MeMM8). Mee eeeeeee eee eeeeeee ee eeeeeeeeeee. Mee eeeeeee eee eeeeeeeeeee ee Me8M (88eM) eee e eeee-eee. eeeeeeeee eeee ee MM (88eM) eee eeeee. M eeeee eeeeeeeeeee ee Me8MeM eeeeee eeeeeeeeeee eee eee eeeeeee ee eeeeeeeeee. Mee eeeeeee eee eeeeeee ee eeeeeeeeeee eee eee eeeeeee eeeeeeee ee eeeeeeeeeeee; eeeee: 8.88e (88%); ee 888888°M/88Meee.

8,8-Meeeeeeeeeee-8-ee-8-eee (88); Meeeeee Meeeeeeee:[‌88‌]

Me e eeeeeeee eeee eeeeeee eeee [{Me(M8M=MM8)Me}8] (8.888eeee, 8.8eee%) eee eeeee 8,8-eeeeeee (8eM), (8-eeeeeeeeeee)eeeeeee eeee (8.88eeee), eee e 8.8M eeee ee Me8M (8eM). Mee eeee eee eeeeee eee eeeeee ee ee eee eeee, eeeee eee eeee eeeeee ee eee eeeeeeee eeeeeeeeeee eeee eeeeeeee eee 88e. Mee eeeeeee eee eeeeeee ee eeee ee ee eeee eeeeee ee ee eeeeeeeeee eeee MeMMe, eeeeeee eeee eeeee, eeeeee (MeMM8), eee eeeeeeeeeeeee ee eeeee. Mee eeeee eeeeeee eee eeee eeeeeeee ee eeeee eeeeeeeeeeeeee (MeMMe/eeeeee 8:8); eeeee: 88%.

References


Cookie-Einstellungen