Directed Metal (Oxo) Aliphatic C–H Hydroxylations: Overriding Substrate Bias
摘要:
The first general strategy for a directing effect on metal (oxo)-promoted C-H hydroxylations is described. Carboxylic acid moieties on the substrate overcome unfavorable electronic, steric, and stereoelectronic biases in C-H hydroxylations catalyzed by the non-heme iron complex Fe(PDP). In a demonstration of the power of this directing effect, C-H oxidation is diverted away from an electronically favored C-1 H abstraction/rearrangement pathway in the paclitaxel framework to enable installation of C-2 oxidation in the naturally occurring oxidation state and stereoconfiguration.
Directed Metal (Oxo) Aliphatic C–H Hydroxylations: Overriding Substrate Bias
作者:Marinus A. Bigi、Sean A. Reed、M. Christina White
DOI:10.1021/ja301685r
日期:2012.6.13
The first general strategy for a directing effect on metal (oxo)-promoted C-H hydroxylations is described. Carboxylic acid moieties on the substrate overcome unfavorable electronic, steric, and stereoelectronic biases in C-H hydroxylations catalyzed by the non-heme iron complex Fe(PDP). In a demonstration of the power of this directing effect, C-H oxidation is diverted away from an electronically favored C-1 H abstraction/rearrangement pathway in the paclitaxel framework to enable installation of C-2 oxidation in the naturally occurring oxidation state and stereoconfiguration.
Hydrogen Bonding Makes a Difference in the Rhodium-Catalyzed Enantioselective Hydrogenation Using Monodentate Phosphoramidites
作者:Yan Liu、Christian A. Sandoval、Yoshiki Yamaguchi、Xue Zhang、Zheng Wang、Koichi Kato、Kuiling Ding
DOI:10.1021/ja063350f
日期:2006.11.1
generation of monodentate phosphoramidite ligands bearing a primary amine moiety was found to display comparable or better efficiency than bisphosphines in the Rh-catalyzed asymmetric hydrogenation of challenging substrates, such as (Z)-methyl alpha-acetoxyacrylate or (E)-beta-aryl itaconate derivatives, affording the corresponding hydrogenation products with excellent enantioselectivities (up to >99%