New Chiral N-Heterocyclic Carbene Ligands in Palladium-Catalyzed α-Arylations of Amides: Conformational Locking through Allylic Strain as a Device for Stereocontrol

被引：84

作者：

Jia, Yi-Xia ^{[1
]}

Katayev, Dmitry ^{[1
]}

Bernardinelli, Gerald ^{[1
]}

Seidel, Thomas M. ^{[1
]}

Kuendig, E. Peter ^{[1
]}

机构：

[1] Univ Geneva, Dept Organ Chem, CH-1211 Geneva 4, Switzerland

来源：

CHEMISTRY-A EUROPEAN JOURNAL | 2010年 / 16卷 / 21期

基金：

瑞士国家科学基金会;

关键词：

arylation; asymmetric catalysis; carbene ligands; N-heterocyclic carbenes; oxindoles; palladium; QUATERNARY STEREOGENIC CENTERS; ASYMMETRIC-SYNTHESIS; ENANTIOSELECTIVE SYNTHESIS; CONJUGATE ADDITIONS; RUTHENIUM CATALYSTS; COMPLEXES BEARING; RHODIUM COMPLEXES; METAL-COMPLEXES; OXINDOLES; NHC;

D O I：

10.1002/chem.201000031

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

New Enders/Herrmann-type chiral N-heterocyclic carbene (NHC) ligands have been developed and applied in asymmetric palladium-catalyzed intramolecular alpha-arylations of amides. The best ligands feature the bulky tert-butyl group and ortho-substituted aryl groups at the stereogenic centers. Aryl bromides readily react at room temperature and aryl chlorides at 50 degrees C. The highly enantiomerically enriched (up to 96% ee) 3-alkyl-3-aryloxindole products were obtained in generally high yields (> 95%) except in cases of steric congestion. The critical roles both of the bulky alkyl group and of the ortho-aryl substituent at the stereogenic center of the ligand were revealed in the crystal structure of a [Pd(eta(3)-allyl)(NHC-L*)(I)] complex. The ligand aryl location and orientation is fixed by conformational locking that minimizes A(1.3)-strain and enables optimal transfer of chiral information.

引用

页码：6300 / 6309

页数：10

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