Potassium Alkenyltrifluoroborates Research Articles

Stereoselective Suzuki−Miyaura Cross-Coupling Reactions of Potassium Alkenyltrifluoroborates with Alkenyl Bromides

[reaction: see text] The stereoselective synthesis of conjugated dienes using air-stable potassium alkenyltrifluoroborates as coupling partners is described. The palladium-catalyzed cross-coupling reaction of potassium (E)- and (Z)-alkenyltrifluoroborates with either (E)- or (Z)-alkenyl bromides proceeds readily with moderate to excellent yields to give the corresponding (E,E)-, (E,Z)-, (Z,E)-, or (Z,Z)-conjugated dienes stereospecifically. The cross-coupling can generally be effected using 5 mol % of Pd(OAc)2, 10 mol % of PPh3, and 3 equiv of Cs2CO3 in THF-H2O (10:1). A variety of functional groups are tolerated in both coupling partners.

Formal Total Synthesis of Oximidine II via a Suzuki‐Type Cross‐Coupling Macrocyclization Employing Potassium Organotrifluoroborates.

A formal total synthesis of oximidine II has been achieved, employing a Suzuki-type coupling approach to construct the highly strained, polyunsaturated 12-membered macrolactone. To achieve this goal, benefit was derived from the stability of potassium alkenyltrifluoroborates to establish conditions for the macrocyclization. The stereocontrolled formation of the cis-1,2-diol subunit was accomplished using a diastereoselective, reagent controlled addition to a chiral aldehyde utilizing the Carreira protocol. Advantage was taken of the Snieckus hydroborating reagent to gain access to the key trifluoroborate needed for the macrocyclization.

Formal total synthesis of oximidine II via a Suzuki-type cross-coupling macrocyclization employing potassium organotrifluoroborates.

A formal total synthesis of oximidine II has been achieved, employing a Suzuki-type coupling approach to construct the highly strained, polyunsaturated 12-membered macrolactone. To achieve this goal, benefit was derived from the stability of potassium alkenyltrifluoroborates to establish conditions for the macrocyclization. The stereocontrolled formation of the cis-1,2-diol subunit was accomplished using a diastereoselective, reagent controlled addition to a chiral aldehyde utilizing the Carreira protocol. Advantage was taken of the Snieckus hydroborating reagent to gain access to the key trifluoroborate needed for the macrocyclization.

Suzuki—Miyaura Cross‐Coupling Reactions of Potassium Alkenyltrifluoroborates.

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Suzuki-Miyaura cross-coupling reactions of potassium alkenyltrifluoroborates.

We have previously reported that the palladium-catalyzed cross-coupling reaction of air-stable potassium alkenyltrifluoroborates with aryl halides and triflates proceeds readily with good yields. Recent progress in outlining the scope and limitations of such reactions is described herein. The palladium-catalyzed cross-coupling reaction of potassium alkenyltrifluoroborates with aryl and heteroaryl halides and triflates proceeds readily with moderate to excellent yields. The alkenyl cross-coupling reaction can generally be effected using 2 mol % of PdCl2(dppf).CH2Cl2 as catalyst in i-PrOH-H2O in the presence of t-BuNH2 as the base. A variety of functional groups are tolerated in both partners, and the process is stereospecific with regard to the alkenyltrifluoroborate starting material.

Suzuki cross-coupling reactions of potassium alkenyltrifluoroborates.

[reaction: see text] The palladium-catalyzed coupling reaction of potassium alkenyltrifluoroborates with aryl or alkenyl halides or triflates proceeds readily with good yields. The trifluoroborates are air- and moisture-stable solids that can be stored indefinitely. The cross-coupling can be effected using PdCl(2)(dppf).CH(2)Cl(2) as the catalyst in n-PrOH in the presence of Et(3)N. A variety of functional groups are tolerated.