Pd(II)-Catalyzed ortho- or meta-C–H Olefination of Phenol Derivatives
摘要:
A combination of weakly coordinating auxiliaries and ligand acceleration allows for the development of both ortho- and meta-selective C-H olefination of phenol derivatives. These reactions demonstrate the feasibility of directing C-H functionalizations when functional groups are distal to target C-H bonds. The meta-C-H functionalization of electron-rich phenol derivatives is unprecedented and orthogonal to previous electrophilic substitution of phenols in terms of regioselectivity. These methods are also applied to functionalize alpha-phenoxyacetic acids, a fibrate class of drug scaffolds.
Pd(II)-Catalyzed <i>ortho</i>- or <i>meta</i>-C–H Olefination of Phenol Derivatives
作者:Hui-Xiong Dai、Gang Li、Xing-Guo Zhang、Antonia F. Stepan、Jin-Quan Yu
DOI:10.1021/ja400659s
日期:2013.5.22
A combination of weakly coordinating auxiliaries and ligand acceleration allows for the development of both ortho- and meta-selective C-H olefination of phenol derivatives. These reactions demonstrate the feasibility of directing C-H functionalizations when functional groups are distal to target C-H bonds. The meta-C-H functionalization of electron-rich phenol derivatives is unprecedented and orthogonal to previous electrophilic substitution of phenols in terms of regioselectivity. These methods are also applied to functionalize alpha-phenoxyacetic acids, a fibrate class of drug scaffolds.
Iridium-Catalyzed Asymmetric Hydrogenation of Sterically Hindered Cyclic Imines for Enantioselective Synthesis of Tetrahydroisoquinolines
An efficient enantioselective hydrogenation of sterically hindered cyclic imines catalyzed by the Ir-tBu-ax-Josiphos complex has been described, producing a series of useful chiral bulky tetrahydroisoquinoline analogs in high isolated yields (85–96%) with good to excellent enantioselectivities (74–99% ee). This transformation provided highly straightforward access to the useful derivatives of tetrahydroisoquinolines