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DFT Investigation of Suzuki–Miyaura Reactions with Aryl Sulfamates Using a Dialkylbiarylphosphine-Ligated Palladium Catalyst
Organometallics ( IF 2.8 ) Pub Date : 2017-09-13 00:00:00 , DOI: 10.1021/acs.organomet.7b00642
Patrick R. Melvin 1 , Ainara Nova 2 , David Balcells 2 , Nilay Hazari 1 , Mats Tilset 2
Affiliation  

Aryl sulfamates are valuable electrophiles for cross-coupling reactions because they can easily be synthesized from phenols and can act as directing groups for C–H bond functionalization prior to cross-coupling. Recently, it was demonstrated that (1-tBu-Indenyl)Pd(XPhos)Cl (XPhos = 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl) is a highly active precatalyst for room-temperature Suzuki–Miyaura couplings of a variety of aryl sulfamates. Herein, we report an in-depth computational investigation into the mechanism of Suzuki–Miyaura reactions with aryl sulfamates using an XPhos-ligated palladium catalyst. Particular emphasis is placed on the turnover-limiting oxidative addition of the aryl sulfamate C–O bond, which has not been studied in detail previously. We show that bidentate coordination of the XPhos ligand via an additional interaction between the biaryl ring and palladium plays a key role in lowering the barrier to oxidative addition. This result is supported by NBO and NCI-Plot analysis on the transition states for oxidative addition. After oxidative addition, the catalytic cycle is completed by transmetalation and reductive elimination, which are both calculated to be facile processes. Our computational findings explain a number of experimental results, including why elevated temperatures are required for the coupling of phenyl sulfamates without electron-withdrawing groups and why aryl carbamate electrophiles are not reactive with this catalyst.

中文翻译:

DFT研究使用二烷基联芳基膦连接的钯催化剂与芳基氨基磺酸盐进行的Suzuki-Miyaura反应

氨基磺酸芳基酯是用于交叉偶联反应的有价值的亲电试剂,因为它们可以很容易地从苯酚中合成,并且可以在交叉偶联之前充当C–H键官能化的导向基团。最近,证明了(1- tBu-Indenyl)Pd(XPhos)Cl(XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl)是室温下各种芳基氨基磺酸酯的Suzuki-Miyaura偶联反应的高活性预催化剂。本文中,我们报告了使用XPhos连接的钯催化剂对铃木-宫浦与氨基磺酸氨基磺酸酯反应的机理进行的深入计算研究。特别强调的是氨基磺酸芳基酯C–O键的营业额限制氧化加成反应,以前没有进行过详细研究。我们表明,XPhos配体通过联芳基环和钯之间的额外相互作用的双齿配位在降低氧化加成的壁垒中起关键作用。NBO和NCI-Plot分析对氧化加成的过渡态均支持该结果。氧化加成后 催化循环通过重金属化和还原消除而完成,两者均被认为是容易实现的过程。我们的计算发现解释了许多实验结果,包括为何不带吸电子基团的氨基磺酸苯酯的偶联需要高温,以及氨基甲酸芳基酯亲电子试剂与该催化剂不反应。
更新日期:2017-09-13
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