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.
作者:UNO, M.、SETO, K.、UEDA, W.、MASUDA, M.、TAKAHASHI, S.
DOI:——
日期:——
An Efficient and Mild CuI/<scp>l</scp>-Proline-Catalyzed Arylation of Acetylacetone or Ethyl Cyanoacetate
作者:Yongwen Jiang、Nan Wu、Haihong Wu、Mingyuan He
DOI:10.1055/s-2005-918921
日期:——
The coupling reaction of aryl iodides with acetylacetone or ethyl cyanoacetate under catalysis of CuI/l-proline works at relatively mild conditions to provide 3-aryl-2, 4-pentanediones and α-aryl cyanoacetates in moderate to good yields.
A highly enantioselective Michaeladdition of alpha-substituted cyanoacetates to vinyl ketones was accomplished in the presence of simple bifunctional thiourea/tertiary amine organocatalysts. A number of alpha-aryl or alkyl cyanoacetates have been successfully applied to give multifunctional compounds with an all-carbon-substituted quaternary stereocenter in excellent enantioselectivities (82-97 %