Reactivity of Planar‐Chiral α‐Ferrocenyl Carbocations towards Electron‐Rich Aromatics
作者:Marcus Korb、Julia Mahrholdt、Xianming Liu、Heinrich Lang
DOI:10.1002/ejic.201801430
日期:2019.2.21
atropselective C,C cross‐coupling reactions for the synthesis of stericallyhindered biaryls, where sandwich compound (Sp)‐1‐(PPh2)‐2‐(o‐NMe2‐C6H4)CH2‐Fc gave an ee of 69 % (1 mol‐% [Pd]), which is up to date the highest observed value for planar‐chiral ferrocenes. The absolute configuration of the chiral ferrocenes was confirmed by single‐crystal X‐ray diffraction analysis. For seleno phosphane 1‐(P(=Se)Ph2)‐2‐(CH2OH)‐Fc
的对映体纯的,平面手性α-二茂铁基碳阳离子(的反应小号p)-2-(P(= S)PH 2)FCCH 2 +(FC =铁(η 5 -C 5 H ^ 5)(η 5 -C 5 H 3))朝着富电子芳烃C 6 H 5 E(E = NH 2,NMe 2,N i Pr 2,NPh 2,PPh 2,P(= S)Ph 2,OH,SH,SMe) E基团的亲核攻击或芳烃在CH处的亲电芳香取代反应报告2 +单位。发现氨基,氧代或硫代官能团在各种产品分布中赋予了相应的二茂铁,而基于P的物种则没有。可以将适当的硫代膦衍生物还原为它们的P III物种,这些化合物用作在阻转性C,C交叉偶联反应中用作支持位配体,以合成位阻联芳基,其中夹心化合物(S p)-1-(PPh 2)-2 -(o -NMe 2 -C 6 H 4)CH 2 -Fc给出了ee为69%(1 mol%[Pd]),这是迄今为止对平面手性二茂铁的最高观测值。手性
Enantioselective Synthesis of Biaryl Compounds via Suzuki–Miyaura Cross-Coupling Using a Palladium Complex of 7′-Butoxy-7-(diphenylphosphino)-8,8′-biquinolyl: Investigation of a New Chiral Ligand Architecture
effective for the synthesis of hindered 2,2′-disubstituted 1,1′-binaphthyls (78–83% yield, 20–38% ee). 7,7′-Dihydroxy-8,8′-biquinolyl was converted to the title phosphine in four-steps via Mitsunobu monoetherification, trifylation, phosphination, and phosphine oxide reduction (63% overall yield). Enantiomericallypure phosphine was combined with Pd2dba3 and investigated for the synthesis of axially chiral
Highly sterically hindered binaphthalene-based monophosphane ligands: synthesis and application in stereoselective Suzuki–Miyaura reactions
作者:Michaela Mešková、Martin Putala
DOI:10.1016/j.tetasy.2013.06.007
日期:2013.8
A series of new sterically hindered (R)-(2′-aryl-1,1′-binaphthalene-2-yl)phosphanes with ortho-substituted phenyls as aryl groups were prepared via Negishi monoarylation of enantiopure 2,2′-dibromo-1,1′-binaphthalene followed by lithiation and quenching with diphenylphosphanyl or dicyclohexylphosphanyl chloride. These ligands were applied to the stereoselective Suzuki–Miyaura coupling for the preparation
Mechanistic and asymmetric investigations of the Au-catalysed cross-coupling between aryldiazonium salts and arylboronic acids using (P,N) gold complexes
performed on gold complexes with (P,N) ligands. Employing 2-pyridylphenyl-diphenylphosphine allowed us to suggest three different mechanistic pathways, starting either with a transmetallation step, via two consecutive single electron transfers, or by implying a transmetallation between Au(I) and Au(III) species. Moreover, when using commercially available chiral (P,N) ligands, the asymmetric formation
Pd(II) complexes of monodentate deoxycholic acid derived binaphthyl diamido phosphites as chiral catalysts in the asymmetric Suzuki-Miyaura cross-coupling
Chiral binaphthyl diamidophosphites derived from deoxycholic acid were synthesized and used as ligands for the preparation of mononuclear Pd(II) complexes, which were employed as catalysts in the asymmetric Suzuki-Miyaura cross-coupling of arylboronic acids with aryl bromides. Among the different reaction parameters, the substrate concentration emerged as being crucial for the outcome of the reaction: the reaction was faster in a concentrated reaction mixture, and could be performed at 0 degrees C, where the reaction promoted by the Pd-complexes was more enantioselective affording cross-coupling products with ee up to 70%. (C) 2017 Elsevier Ltd. All rights reserved.