Managing Highly Coordinative Substrates in Asymmetric Catalysis: A Catalytic Asymmetric Amination with a Lanthanum-Based Ternary Catalyst
摘要:
Full details of a catalytic asymmetric amination with a lanthanum/amide-based ligand catalyst system are described. A catalyst comprising La(NO3)(3)center dot 6H(2)O, (R)-3a and H-D-Val-V'Bu was identified to promote the catalytic asymmetric amination of nonprotected succinimide derivative 1 with as little as 1 mol % catalyst loading Mechanistic studies by various spectroscopic analyses and several control and kinetic experiments suggested that the catalyst components were in equilibrium between the associated and dissociated forms, and that the reaction likely proceeded through a La(NO3)(3)center dot 6H(2)O/(R)-3a/H-D-Val-O'Bu ternary complex. This catalyst system was also effective for asymmetric amination of N-nonsubstituted alpha-alkoxycarbonyl amides 7, hitherto unprecedented substrates in asymmetric catalysis, probably due to their attenuated reactivity and difficult stereocontrol, affording the amination products in up to > 99% yield and > 99% ee. The high catalytic performance and enantiocontrol of the reaction with highly coordinative substrates were achieved by the activation/recognition of the substrates exerted by coordination to lanthanum and hydrogen bonding cooperatively in the transition state.
Managing Highly Coordinative Substrates in Asymmetric Catalysis: A Catalytic Asymmetric Amination with a Lanthanum-Based Ternary Catalyst
摘要:
Full details of a catalytic asymmetric amination with a lanthanum/amide-based ligand catalyst system are described. A catalyst comprising La(NO3)(3)center dot 6H(2)O, (R)-3a and H-D-Val-V'Bu was identified to promote the catalytic asymmetric amination of nonprotected succinimide derivative 1 with as little as 1 mol % catalyst loading Mechanistic studies by various spectroscopic analyses and several control and kinetic experiments suggested that the catalyst components were in equilibrium between the associated and dissociated forms, and that the reaction likely proceeded through a La(NO3)(3)center dot 6H(2)O/(R)-3a/H-D-Val-O'Bu ternary complex. This catalyst system was also effective for asymmetric amination of N-nonsubstituted alpha-alkoxycarbonyl amides 7, hitherto unprecedented substrates in asymmetric catalysis, probably due to their attenuated reactivity and difficult stereocontrol, affording the amination products in up to > 99% yield and > 99% ee. The high catalytic performance and enantiocontrol of the reaction with highly coordinative substrates were achieved by the activation/recognition of the substrates exerted by coordination to lanthanum and hydrogen bonding cooperatively in the transition state.
Catalytic asymmetric hydroxylation of α-alkoxycarbonyl amides with a Pr(OiPr)3/amide-based ligand catalyst
作者:Sho Takechi、Naoya Kumagai、Masakatsu Shibasaki
DOI:10.1016/j.tetlet.2010.11.064
日期:2011.4
A catalytic asymmetric hydroxylation of N-nonsubstituted alpha-alkoxycarbonyl amides is described. A new effective catalyst comprising Pr((OPr)-Pr-i)(3) and a fluoro-substituted amide-based ligand was identified using oxaziridine as the oxidizing reagent. The catalyst components were in dynamic equilibrium in the reaction mixture, which assembled to form the associated transition state through metal coordination and hydrogen bonding. (C) 2010 Elsevier Ltd. All rights reserved.
Managing Highly Coordinative Substrates in Asymmetric Catalysis: A Catalytic Asymmetric Amination with a Lanthanum-Based Ternary Catalyst
Full details of a catalytic asymmetric amination with a lanthanum/amide-based ligand catalyst system are described. A catalyst comprising La(NO3)(3)center dot 6H(2)O, (R)-3a and H-D-Val-V'Bu was identified to promote the catalytic asymmetric amination of nonprotected succinimide derivative 1 with as little as 1 mol % catalyst loading Mechanistic studies by various spectroscopic analyses and several control and kinetic experiments suggested that the catalyst components were in equilibrium between the associated and dissociated forms, and that the reaction likely proceeded through a La(NO3)(3)center dot 6H(2)O/(R)-3a/H-D-Val-O'Bu ternary complex. This catalyst system was also effective for asymmetric amination of N-nonsubstituted alpha-alkoxycarbonyl amides 7, hitherto unprecedented substrates in asymmetric catalysis, probably due to their attenuated reactivity and difficult stereocontrol, affording the amination products in up to > 99% yield and > 99% ee. The high catalytic performance and enantiocontrol of the reaction with highly coordinative substrates were achieved by the activation/recognition of the substrates exerted by coordination to lanthanum and hydrogen bonding cooperatively in the transition state.