Generating Active 鈥淟-Pd(0)鈥?via Neutral or Cationic 蟺-Allylpalladium Complexes Featuring Biaryl/Bipyrazolylphosphines: Synthetic, Mechanistic, and Structure鈥揂ctivity Studies in Challenging Cross-Coupl

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• 作者：A. J. DeAngelis ; Peter G. Gildner ; Ruishan Chow ; Thomas J. Colacot
• 刊名：Journal of Organic Chemistry
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：80
• 期：13
• 页码：6794-6813
• 全文大小：894K
• ISSN：1520-6904

文摘

Two new classes of highly active yet air- and moisture-stable 蟺-R-allylpalladium complexes containing bulky biaryl- and bipyrazolylphosphines with extremely broad ligand scope have been developed. Neutral 蟺-allylpalladium complexes incorporated a range of biaryl/bipyrazolylphosphine ligands, while extremely bulky ligands were accommodated by a cationic scaffold. These complexes are easily activated under mild conditions and are efficient for a wide array of challenging C鈥揅 and C鈥揦 (X = heteroatom) cross-coupling reactions. Their high activity is correlated to their facile activation to a 12-electron-based 鈥淟-Pd(0)鈥?catalyst under commonly employed conditions for cross-coupling reactions, noninhibitory byproduct release upon activation, and suppression of the off-cycle pathway to form dinuclear (渭-allyl)(渭-Cl)Pd₂(L)₂ species, supported by structural (single crystal X-ray) and kinetic studies. A broad scope of C鈥揅 and C鈥揦 coupling reactions with low catalyst loadings and short reaction times highlight the versatility and practicality of these catalysts in organic synthesis.